diff --git a/app/api.js b/app/api.js
index 42d7d512..7ec1341e 100644
--- a/app/api.js
+++ b/app/api.js
@@ -91,47 +91,107 @@ export async function setPassword(id, owner_token, keychain) {
   return response.ok;
 }
 
-export function uploadFile(
-  encrypted,
-  metadata,
-  verifierB64,
-  keychain,
-  onprogress
-) {
-  const xhr = new XMLHttpRequest();
-  const upload = {
-    cancel: function() {
-      xhr.abort();
-    },
-    result: new Promise(function(resolve, reject) {
-      xhr.addEventListener('loadend', function() {
-        const authHeader = xhr.getResponseHeader('WWW-Authenticate');
-        if (authHeader) {
-          keychain.nonce = parseNonce(authHeader);
-        }
-        if (xhr.status === 200) {
-          const responseObj = JSON.parse(xhr.responseText);
-          return resolve({
-            url: responseObj.url,
-            id: responseObj.id,
-            ownerToken: responseObj.owner
+function asyncInitWebSocket(server) {
+  return new Promise(resolve => {
+    const ws = new WebSocket(server);
+    ws.onopen = () => {
+      resolve(ws);
+    };
+  });
+}
+
+function listenForResponse(ws, canceller) {
+  return new Promise((resolve, reject) => {
+    ws.addEventListener('message', function(msg) {
+      try {
+        const response = JSON.parse(msg.data);
+        if (response.error) {
+          throw new Error(response.error);
+        } else {
+          resolve({
+            url: response.url,
+            id: response.id,
+            ownerToken: response.owner
           });
         }
-        reject(new Error(xhr.status));
-      });
-    })
-  };
-  const blob = new Blob([encrypted], { type: 'application/octet-stream' });
-  xhr.upload.addEventListener('progress', function(event) {
-    if (event.lengthComputable) {
-      onprogress([event.loaded, event.total]);
-    }
+      } catch (e) {
+        ws.close();
+        canceller.cancelled = true;
+        canceller.error = e;
+        reject(e);
+      }
+    });
   });
-  xhr.open('post', '/api/upload', true);
-  xhr.setRequestHeader('X-File-Metadata', arrayToB64(new Uint8Array(metadata)));
-  xhr.setRequestHeader('Authorization', `send-v1 ${verifierB64}`);
-  xhr.send(blob);
-  return upload;
+}
+
+async function upload(
+  stream,
+  streamInfo,
+  metadata,
+  verifierB64,
+  onprogress,
+  canceller
+) {
+  const host = window.location.hostname;
+  const port = window.location.port;
+  const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
+  const ws = await asyncInitWebSocket(`${protocol}//${host}:${port}/api/ws`);
+
+  try {
+    const metadataHeader = arrayToB64(new Uint8Array(metadata));
+    const fileMeta = {
+      fileMetadata: metadataHeader,
+      authorization: `send-v1 ${verifierB64}`
+    };
+
+    const responsePromise = listenForResponse(ws, canceller);
+
+    ws.send(JSON.stringify(fileMeta));
+
+    const reader = stream.getReader();
+    let state = await reader.read();
+    let size = 0;
+    while (!state.done) {
+      const buf = state.value;
+      if (canceller.cancelled) {
+        throw canceller.error;
+      }
+
+      ws.send(buf);
+
+      onprogress([Math.min(streamInfo.fileSize, size), streamInfo.fileSize]);
+      size += streamInfo.recordSize;
+      state = await reader.read();
+    }
+    const footer = new Uint8Array([0]);
+    ws.send(footer);
+
+    const response = await responsePromise; //promise only fufills if response is good
+    ws.close();
+    return response;
+  } catch (e) {
+    ws.close(4000);
+    throw e;
+  }
+}
+
+export function uploadWs(encrypted, info, metadata, verifierB64, onprogress) {
+  const canceller = { cancelled: false };
+
+  return {
+    cancel: function() {
+      canceller.error = new Error(0);
+      canceller.cancelled = true;
+    },
+    result: upload(
+      encrypted,
+      info,
+      metadata,
+      verifierB64,
+      onprogress,
+      canceller
+    )
+  };
 }
 
 function download(id, keychain, onprogress, canceller) {
@@ -151,11 +211,7 @@ function download(id, keychain, onprogress, canceller) {
       }
 
       const blob = new Blob([xhr.response]);
-      const fileReader = new FileReader();
-      fileReader.readAsArrayBuffer(blob);
-      fileReader.onload = function() {
-        resolve(this.result);
-      };
+      resolve(blob);
     });
     xhr.addEventListener('progress', function(event) {
       if (event.lengthComputable && event.target.status === 200) {
diff --git a/app/ece.js b/app/ece.js
new file mode 100644
index 00000000..eb86c6c0
--- /dev/null
+++ b/app/ece.js
@@ -0,0 +1,292 @@
+require('buffer');
+import { ReadableStream, TransformStream } from 'web-streams-polyfill';
+
+const NONCE_LENGTH = 12;
+const TAG_LENGTH = 16;
+const KEY_LENGTH = 16;
+const MODE_ENCRYPT = 'encrypt';
+const MODE_DECRYPT = 'decrypt';
+const RS = 1048576;
+
+const encoder = new TextEncoder();
+
+function generateSalt(len) {
+  const randSalt = new Uint8Array(len);
+  window.crypto.getRandomValues(randSalt);
+  return randSalt.buffer;
+}
+
+class ECETransformer {
+  constructor(mode, ikm, rs, salt) {
+    this.mode = mode;
+    this.prevChunk;
+    this.seq = 0;
+    this.firstchunk = true;
+    this.rs = rs;
+    this.ikm = ikm.buffer;
+    this.salt = salt;
+  }
+
+  async generateKey() {
+    const inputKey = await window.crypto.subtle.importKey(
+      'raw',
+      this.ikm,
+      'HKDF',
+      false,
+      ['deriveKey']
+    );
+
+    return window.crypto.subtle.deriveKey(
+      {
+        name: 'HKDF',
+        salt: this.salt,
+        info: encoder.encode('Content-Encoding: aes128gcm\0'),
+        hash: 'SHA-256'
+      },
+      inputKey,
+      {
+        name: 'AES-GCM',
+        length: 128
+      },
+      false,
+      ['encrypt', 'decrypt']
+    );
+  }
+
+  async generateNonceBase() {
+    const inputKey = await window.crypto.subtle.importKey(
+      'raw',
+      this.ikm,
+      'HKDF',
+      false,
+      ['deriveKey']
+    );
+
+    const base = await window.crypto.subtle.exportKey(
+      'raw',
+      await window.crypto.subtle.deriveKey(
+        {
+          name: 'HKDF',
+          salt: this.salt,
+          info: encoder.encode('Content-Encoding: nonce\0'),
+          hash: 'SHA-256'
+        },
+        inputKey,
+        {
+          name: 'AES-GCM',
+          length: 128
+        },
+        true,
+        ['encrypt', 'decrypt']
+      )
+    );
+
+    return Buffer.from(base.slice(0, NONCE_LENGTH));
+  }
+
+  generateNonce(seq) {
+    if (seq > 0xffffffff) {
+      throw new Error('record sequence number exceeds limit');
+    }
+    const nonce = Buffer.from(this.nonceBase);
+    const m = nonce.readUIntBE(nonce.length - 4, 4);
+    const xor = (m ^ seq) >>> 0; //forces unsigned int xor
+    nonce.writeUIntBE(xor, nonce.length - 4, 4);
+
+    return nonce;
+  }
+
+  pad(data, isLast) {
+    const len = data.length;
+    if (len + TAG_LENGTH >= this.rs) {
+      throw new Error('data too large for record size');
+    }
+
+    if (isLast) {
+      const padding = Buffer.alloc(1);
+      padding.writeUInt8(2, 0);
+      return Buffer.concat([data, padding]);
+    } else {
+      const padding = Buffer.alloc(this.rs - len - TAG_LENGTH);
+      padding.fill(0);
+      padding.writeUInt8(1, 0);
+      return Buffer.concat([data, padding]);
+    }
+  }
+
+  unpad(data, isLast) {
+    for (let i = data.length - 1; i >= 0; i--) {
+      if (data[i]) {
+        if (isLast) {
+          if (data[i] !== 2) {
+            throw new Error('delimiter of final record is not 2');
+          }
+        } else {
+          if (data[i] !== 1) {
+            throw new Error('delimiter of not final record is not 1');
+          }
+        }
+        return data.slice(0, i);
+      }
+    }
+    throw new Error('no delimiter found');
+  }
+
+  createHeader() {
+    const nums = Buffer.alloc(5);
+    nums.writeUIntBE(this.rs, 0, 4);
+    nums.writeUIntBE(0, 4, 1);
+    return Buffer.concat([Buffer.from(this.salt), nums]);
+  }
+
+  readHeader(buffer) {
+    if (buffer.length < 21) {
+      throw new Error('chunk too small for reading header');
+    }
+    const header = {};
+    header.salt = buffer.buffer.slice(0, KEY_LENGTH);
+    header.rs = buffer.readUIntBE(KEY_LENGTH, 4);
+    const idlen = buffer.readUInt8(KEY_LENGTH + 4);
+    header.length = idlen + KEY_LENGTH + 5;
+    return header;
+  }
+
+  async encryptRecord(buffer, seq, isLast) {
+    const nonce = this.generateNonce(seq);
+    const encrypted = await window.crypto.subtle.encrypt(
+      { name: 'AES-GCM', iv: nonce },
+      this.key,
+      this.pad(buffer, isLast)
+    );
+    return Buffer.from(encrypted);
+  }
+
+  async decryptRecord(buffer, seq, isLast) {
+    const nonce = this.generateNonce(seq);
+    const data = await window.crypto.subtle.decrypt(
+      {
+        name: 'AES-GCM',
+        iv: nonce,
+        tagLength: 128
+      },
+      this.key,
+      buffer
+    );
+
+    return this.unpad(Buffer.from(data), isLast);
+  }
+
+  async start(controller) {
+    if (this.mode === MODE_ENCRYPT) {
+      this.key = await this.generateKey();
+      this.nonceBase = await this.generateNonceBase();
+      controller.enqueue(this.createHeader());
+    } else if (this.mode !== MODE_DECRYPT) {
+      throw new Error('mode must be either encrypt or decrypt');
+    }
+  }
+
+  async transformPrevChunk(isLast, controller) {
+    if (this.mode === MODE_ENCRYPT) {
+      controller.enqueue(
+        await this.encryptRecord(this.prevChunk, this.seq, isLast)
+      );
+      this.seq++;
+    } else {
+      if (this.seq === 0) {
+        //the first chunk during decryption contains only the header
+        const header = this.readHeader(this.prevChunk);
+        this.salt = header.salt;
+        this.rs = header.rs;
+        this.key = await this.generateKey();
+        this.nonceBase = await this.generateNonceBase();
+      } else {
+        controller.enqueue(
+          await this.decryptRecord(this.prevChunk, this.seq - 1, isLast)
+        );
+      }
+      this.seq++;
+    }
+  }
+
+  async transform(chunk, controller) {
+    if (!this.firstchunk) {
+      await this.transformPrevChunk(false, controller);
+    }
+    this.firstchunk = false;
+    this.prevChunk = Buffer.from(chunk.buffer);
+  }
+
+  async flush(controller) {
+    if (this.prevChunk) {
+      await this.transformPrevChunk(true, controller);
+    }
+  }
+}
+
+class BlobSlicer {
+  constructor(blob, rs, mode) {
+    this.blob = blob;
+    this.index = 0;
+    this.mode = mode;
+    this.chunkSize = mode === MODE_ENCRYPT ? rs - 17 : rs;
+  }
+
+  pull(controller) {
+    return new Promise((resolve, reject) => {
+      const bytesLeft = this.blob.size - this.index;
+      if (bytesLeft <= 0) {
+        controller.close();
+        return resolve();
+      }
+      let size = 1;
+      if (this.mode === MODE_DECRYPT && this.index === 0) {
+        size = Math.min(21, bytesLeft);
+      } else {
+        size = Math.min(this.chunkSize, bytesLeft);
+      }
+      const blob = this.blob.slice(this.index, this.index + size);
+      const reader = new FileReader();
+      reader.onload = () => {
+        controller.enqueue(new Uint8Array(reader.result));
+        resolve();
+      };
+      reader.onerror = reject;
+      reader.readAsArrayBuffer(blob);
+      this.index += size;
+    });
+  }
+}
+
+class BlobSliceStream extends ReadableStream {
+  constructor(blob, size, mode) {
+    super(new BlobSlicer(blob, size, mode));
+  }
+}
+
+/*
+input: a blob containing data to be transformed
+key:  Uint8Array containing key of size KEY_LENGTH 
+mode: string, either 'encrypt' or 'decrypt'
+rs:   int containing record size, optional
+salt: ArrayBuffer containing salt of KEY_LENGTH length, optional
+*/
+export default class ECE {
+  constructor(input, key, mode, rs, salt) {
+    if (rs === undefined) {
+      rs = RS;
+    }
+    if (salt === undefined) {
+      salt = generateSalt(KEY_LENGTH);
+    }
+
+    this.streamInfo = {
+      recordSize: rs,
+      fileSize: 21 + input.size + 16 * Math.floor(input.size / (rs - 17))
+    };
+    const inputStream = new BlobSliceStream(input, rs, mode);
+
+    const ts = new TransformStream(new ECETransformer(mode, key, rs, salt));
+    this.stream = inputStream.pipeThrough(ts);
+  }
+}
diff --git a/app/fileManager.js b/app/fileManager.js
index 786f99f8..e29a05e2 100644
--- a/app/fileManager.js
+++ b/app/fileManager.js
@@ -52,7 +52,7 @@ export default function(state, emitter) {
     checkFiles();
   });
 
-  emitter.on('navigate', checkFiles);
+  //emitter.on('navigate', checkFiles);
 
   emitter.on('render', () => {
     lastRender = Date.now();
diff --git a/app/fileReceiver.js b/app/fileReceiver.js
index 27dccf6d..2a22fbca 100644
--- a/app/fileReceiver.js
+++ b/app/fileReceiver.js
@@ -51,6 +51,21 @@ export default class FileReceiver extends Nanobus {
     this.state = 'ready';
   }
 
+  async streamToArrayBuffer(stream, streamSize) {
+    const reader = stream.getReader();
+    const result = new Uint8Array(streamSize);
+    let offset = 0;
+
+    let state = await reader.read();
+    while (!state.done) {
+      result.set(state.value, offset);
+      offset += state.value.length;
+      state = await reader.read();
+    }
+
+    return result.buffer;
+  }
+
   async download(noSave = false) {
     this.state = 'downloading';
     this.downloadRequest = await downloadFile(
@@ -61,13 +76,21 @@ export default class FileReceiver extends Nanobus {
         this.emit('progress');
       }
     );
+
     try {
       const ciphertext = await this.downloadRequest.result;
       this.downloadRequest = null;
       this.msg = 'decryptingFile';
       this.state = 'decrypting';
       this.emit('decrypting');
-      const plaintext = await this.keychain.decryptFile(ciphertext);
+
+      const dec = await this.keychain.decryptStream(ciphertext);
+      const plainstream = dec.stream;
+      const plaintext = await this.streamToArrayBuffer(
+        plainstream,
+        dec.streamInfo.fileSize
+      );
+
       if (!noSave) {
         await saveFile({
           plaintext,
diff --git a/app/fileSender.js b/app/fileSender.js
index 99f2ad12..7c3c4de1 100644
--- a/app/fileSender.js
+++ b/app/fileSender.js
@@ -3,7 +3,7 @@ import Nanobus from 'nanobus';
 import OwnedFile from './ownedFile';
 import Keychain from './keychain';
 import { arrayToB64, bytes } from './utils';
-import { uploadFile } from './api';
+import { uploadWs } from './api';
 
 export default class FileSender extends Nanobus {
   constructor(file) {
@@ -59,28 +59,31 @@ export default class FileSender extends Nanobus {
 
   async upload() {
     const start = Date.now();
-    const plaintext = await this.readFile();
     if (this.cancelled) {
       throw new Error(0);
     }
     this.msg = 'encryptingFile';
     this.emit('encrypting');
-    const encrypted = await this.keychain.encryptFile(plaintext);
+
+    const enc = this.keychain.encryptStream(this.file);
     const metadata = await this.keychain.encryptMetadata(this.file);
     const authKeyB64 = await this.keychain.authKeyB64();
-    if (this.cancelled) {
-      throw new Error(0);
-    }
-    this.uploadRequest = uploadFile(
-      encrypted,
+
+    this.uploadRequest = uploadWs(
+      enc.stream,
+      enc.streamInfo,
       metadata,
       authKeyB64,
-      this.keychain,
       p => {
         this.progress = p;
         this.emit('progress');
       }
     );
+
+    if (this.cancelled) {
+      throw new Error(0);
+    }
+
     this.msg = 'fileSizeProgress';
     this.emit('progress'); // HACK to kick MS Edge
     try {
diff --git a/app/keychain.js b/app/keychain.js
index eacffec3..75778990 100644
--- a/app/keychain.js
+++ b/app/keychain.js
@@ -1,5 +1,5 @@
 import { arrayToB64, b64ToArray } from './utils';
-
+import ECE from './ece.js';
 const encoder = new TextEncoder();
 const decoder = new TextDecoder();
 
@@ -179,6 +179,16 @@ export default class Keychain {
     return ciphertext;
   }
 
+  encryptStream(plaintext) {
+    const enc = new ECE(plaintext, this.rawSecret, 'encrypt');
+    return enc;
+  }
+
+  decryptStream(encstream) {
+    const dec = new ECE(encstream, this.rawSecret, 'decrypt');
+    return dec;
+  }
+
   async decryptFile(ciphertext) {
     const encryptKey = await this.encryptKeyPromise;
     const plaintext = await window.crypto.subtle.decrypt(
diff --git a/docs/build.md b/docs/build.md
index 78ebd66f..f440f410 100644
--- a/docs/build.md
+++ b/docs/build.md
@@ -2,11 +2,11 @@ Send has two build configurations, development and production. Both can be run v
 
 # Development
 
-`npm start` launches a `webpack-dev-server` on port 8080 that compiles the assets and watches files for changes. It also serves the backend API and frontend unit tests via the `server/dev.js` entrypoint. The frontend tests can be run in the browser by navigating to http://localhost:8080/test and will rerun automatically as the watched files are saved with changes.
+`npm start` launches a `webpack-dev-server` on port 8080 that compiles the assets and watches files for changes. It also serves the backend API and frontend unit tests via the `server/bin/dev.js` entrypoint. The frontend tests can be run in the browser by navigating to http://localhost:8080/test and will rerun automatically as the watched files are saved with changes.
 
 # Production
 
-`npm run build` compiles the assets and writes the files to the `dist/` directory. `npm run prod` launches an Express server on port 1443 that serves the backend API and frontend static assets from `dist/` via the `server/prod.js` entrypoint.
+`npm run build` compiles the assets and writes the files to the `dist/` directory. `npm run prod` launches an Express server on port 1443 that serves the backend API and frontend static assets from `dist/` via the `server/bin/prod.js` entrypoint.
 
 # Notable differences
 
diff --git a/package-lock.json b/package-lock.json
index 509909c1..6247b8a6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -485,8 +485,7 @@
     "async-limiter": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/async-limiter/-/async-limiter-1.0.0.tgz",
-      "integrity": "sha512-jp/uFnooOiO+L211eZOoSyzpOITMXx1rBITauYykG3BRYPu8h0UcxsPNB04RR5vo4Tyz3+ay17tR6JVf9qzYWg==",
-      "dev": true
+      "integrity": "sha512-jp/uFnooOiO+L211eZOoSyzpOITMXx1rBITauYykG3BRYPu8h0UcxsPNB04RR5vo4Tyz3+ay17tR6JVf9qzYWg=="
     },
     "asynckit": {
       "version": "0.4.0",
@@ -2613,8 +2612,7 @@
     "core-util-is": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.2.tgz",
-      "integrity": "sha1-tf1UIgqivFq1eqtxQMlAdUUDwac=",
-      "dev": true
+      "integrity": "sha1-tf1UIgqivFq1eqtxQMlAdUUDwac="
     },
     "cosmiconfig": {
       "version": "4.0.0",
@@ -3628,7 +3626,6 @@
       "version": "3.5.4",
       "resolved": "https://registry.npmjs.org/duplexify/-/duplexify-3.5.4.tgz",
       "integrity": "sha512-JzYSLYMhoVVBe8+mbHQ4KgpvHpm0DZpJuL8PY93Vyv1fW7jYJ90LoXa1di/CVbJM+TgMs91rbDapE/RNIfnJsA==",
-      "dev": true,
       "requires": {
         "end-of-stream": "1.4.1",
         "inherits": "2.0.3",
@@ -3640,7 +3637,6 @@
           "version": "2.3.5",
           "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.5.tgz",
           "integrity": "sha512-tK0yDhrkygt/knjowCUiWP9YdV7c5R+8cR0r/kt9ZhBU906Fs6RpQJCEilamRJj1Nx2rWI6LkW9gKqjTkshhEw==",
-          "dev": true,
           "requires": {
             "core-util-is": "1.0.2",
             "inherits": "2.0.3",
@@ -3655,7 +3651,6 @@
           "version": "1.0.3",
           "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.0.3.tgz",
           "integrity": "sha512-4AH6Z5fzNNBcH+6XDMfA/BTt87skxqJlO0lAh3Dker5zThcAxG6mKz+iGu308UKoPPQ8Dcqx/4JhujzltRa+hQ==",
-          "dev": true,
           "requires": {
             "safe-buffer": "5.1.1"
           }
@@ -3719,7 +3714,6 @@
       "version": "1.4.1",
       "resolved": "https://registry.npmjs.org/end-of-stream/-/end-of-stream-1.4.1.tgz",
       "integrity": "sha512-1MkrZNvWTKCaigbn+W15elq2BB/L22nqrSY5DKlo3X6+vclJm8Bb5djXJBmEX6fS3+zCh/F4VBK5Z2KxJt4s2Q==",
-      "dev": true,
       "requires": {
         "once": "1.4.0"
       }
@@ -4373,6 +4367,14 @@
         }
       }
     },
+    "express-ws": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/express-ws/-/express-ws-4.0.0.tgz",
+      "integrity": "sha512-KEyUw8AwRET2iFjFsI1EJQrJ/fHeGiJtgpYgEWG3yDv4l/To/m3a2GaYfeGyB3lsWdvbesjF5XCMx+SVBgAAYw==",
+      "requires": {
+        "ws": "5.2.0"
+      }
+    },
     "extend": {
       "version": "3.0.1",
       "resolved": "https://registry.npmjs.org/extend/-/extend-3.0.1.tgz",
@@ -6496,6 +6498,15 @@
         "ctype": "0.5.3"
       }
     },
+    "http_ece": {
+      "version": "1.0.5",
+      "resolved": "https://registry.npmjs.org/http_ece/-/http_ece-1.0.5.tgz",
+      "integrity": "sha1-tgZg+q8UIVEC0Uk+pyDc2StTNy8=",
+      "dev": true,
+      "requires": {
+        "urlsafe-base64": "1.0.0"
+      }
+    },
     "https-browserify": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/https-browserify/-/https-browserify-1.0.0.tgz",
@@ -12113,7 +12124,6 @@
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
       "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
-      "dev": true,
       "requires": {
         "wrappy": "1.0.2"
       }
@@ -15771,8 +15781,7 @@
     "process-nextick-args": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.0.tgz",
-      "integrity": "sha512-MtEC1TqN0EU5nephaJ4rAtThHtC86dNN9qCuEhtshvpVBkAW5ZO7BASN9REnF9eoXGcRub+pFuKEpOHE+HbEMw==",
-      "dev": true
+      "integrity": "sha512-MtEC1TqN0EU5nephaJ4rAtThHtC86dNN9qCuEhtshvpVBkAW5ZO7BASN9REnF9eoXGcRub+pFuKEpOHE+HbEMw=="
     },
     "progress": {
       "version": "2.0.0",
@@ -15894,6 +15903,19 @@
         "proxy-from-env": "1.0.0",
         "rimraf": "2.6.2",
         "ws": "3.3.3"
+      },
+      "dependencies": {
+        "ws": {
+          "version": "3.3.3",
+          "resolved": "https://registry.npmjs.org/ws/-/ws-3.3.3.tgz",
+          "integrity": "sha512-nnWLa/NwZSt4KQJu51MYlCcSQ5g7INpOrOMt4XV8j4dqTXdmlUmSHQ8/oLC069ckre0fRsgfvsKwbTdtKLCDkA==",
+          "dev": true,
+          "requires": {
+            "async-limiter": "1.0.0",
+            "safe-buffer": "5.1.1",
+            "ultron": "1.1.1"
+          }
+        }
       }
     },
     "q": {
@@ -17655,8 +17677,7 @@
     "stream-shift": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/stream-shift/-/stream-shift-1.0.0.tgz",
-      "integrity": "sha1-1cdSgl5TZ+eG944Y5EXqIjoVWVI=",
-      "dev": true
+      "integrity": "sha1-1cdSgl5TZ+eG944Y5EXqIjoVWVI="
     },
     "stream-to-observable": {
       "version": "0.2.0",
@@ -18713,8 +18734,7 @@
     "ultron": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/ultron/-/ultron-1.1.1.tgz",
-      "integrity": "sha512-UIEXBNeYmKptWH6z8ZnqTeS8fV74zG0/eRU9VGkpzz+LIJNs8W/zM/L+7ctCkRrgbNnnR0xxw4bKOr0cW0N0Og==",
-      "dev": true
+      "integrity": "sha512-UIEXBNeYmKptWH6z8ZnqTeS8fV74zG0/eRU9VGkpzz+LIJNs8W/zM/L+7ctCkRrgbNnnR0xxw4bKOr0cW0N0Og=="
     },
     "unassert": {
       "version": "1.5.1",
@@ -19004,6 +19024,12 @@
         }
       }
     },
+    "urlsafe-base64": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/urlsafe-base64/-/urlsafe-base64-1.0.0.tgz",
+      "integrity": "sha1-I/iQaabGL0bPOh07ABac77kL4MY=",
+      "dev": true
+    },
     "use": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/use/-/use-2.0.2.tgz",
@@ -19123,8 +19149,7 @@
     "util-deprecate": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
-      "integrity": "sha1-RQ1Nyfpw3nMnYvvS1KKJgUGaDM8=",
-      "dev": true
+      "integrity": "sha1-RQ1Nyfpw3nMnYvvS1KKJgUGaDM8="
     },
     "util.promisify": {
       "version": "1.0.0",
@@ -19295,6 +19320,12 @@
         "minimalistic-assert": "1.0.0"
       }
     },
+    "web-streams-polyfill": {
+      "version": "1.3.2",
+      "resolved": "https://registry.npmjs.org/web-streams-polyfill/-/web-streams-polyfill-1.3.2.tgz",
+      "integrity": "sha1-NxkkXpCSgtk5Z4JfRLzVUOnAOZU=",
+      "dev": true
+    },
     "webidl-conversions": {
       "version": "4.0.2",
       "resolved": "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-4.0.2.tgz",
@@ -19794,6 +19825,53 @@
       "integrity": "sha512-nqHUnMXmBzT0w570r2JpJxfiSD1IzoI+HGVdd3aZ0yNi3ngvQ4jv1dtHt5VGxfI2yj5yqImPhOK4vmIh2xMbGg==",
       "dev": true
     },
+    "websocket-stream": {
+      "version": "5.1.2",
+      "resolved": "https://registry.npmjs.org/websocket-stream/-/websocket-stream-5.1.2.tgz",
+      "integrity": "sha512-lchLOk435iDWs0jNuL+hiU14i3ERSrMA0IKSiJh7z6X/i4XNsutBZrtqu2CPOZuA4G/zabiqVAos0vW+S7GEVw==",
+      "requires": {
+        "duplexify": "3.5.4",
+        "inherits": "2.0.3",
+        "readable-stream": "2.3.6",
+        "safe-buffer": "5.1.1",
+        "ws": "3.3.3",
+        "xtend": "4.0.1"
+      },
+      "dependencies": {
+        "readable-stream": {
+          "version": "2.3.6",
+          "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.6.tgz",
+          "integrity": "sha512-tQtKA9WIAhBF3+VLAseyMqZeBjW0AHJoxOtYqSUZNJxauErmLbVm2FW1y+J/YA9dUrAC39ITejlZWhVIwawkKw==",
+          "requires": {
+            "core-util-is": "1.0.2",
+            "inherits": "2.0.3",
+            "isarray": "1.0.0",
+            "process-nextick-args": "2.0.0",
+            "safe-buffer": "5.1.1",
+            "string_decoder": "1.1.1",
+            "util-deprecate": "1.0.2"
+          }
+        },
+        "string_decoder": {
+          "version": "1.1.1",
+          "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
+          "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
+          "requires": {
+            "safe-buffer": "5.1.1"
+          }
+        },
+        "ws": {
+          "version": "3.3.3",
+          "resolved": "https://registry.npmjs.org/ws/-/ws-3.3.3.tgz",
+          "integrity": "sha512-nnWLa/NwZSt4KQJu51MYlCcSQ5g7INpOrOMt4XV8j4dqTXdmlUmSHQ8/oLC069ckre0fRsgfvsKwbTdtKLCDkA==",
+          "requires": {
+            "async-limiter": "1.0.0",
+            "safe-buffer": "5.1.1",
+            "ultron": "1.1.1"
+          }
+        }
+      }
+    },
     "whatwg-encoding": {
       "version": "1.0.3",
       "resolved": "https://registry.npmjs.org/whatwg-encoding/-/whatwg-encoding-1.0.3.tgz",
@@ -19882,8 +19960,7 @@
     "wrappy": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
-      "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8=",
-      "dev": true
+      "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8="
     },
     "wreck": {
       "version": "12.5.1",
@@ -19922,14 +19999,11 @@
       }
     },
     "ws": {
-      "version": "3.3.3",
-      "resolved": "https://registry.npmjs.org/ws/-/ws-3.3.3.tgz",
-      "integrity": "sha512-nnWLa/NwZSt4KQJu51MYlCcSQ5g7INpOrOMt4XV8j4dqTXdmlUmSHQ8/oLC069ckre0fRsgfvsKwbTdtKLCDkA==",
-      "dev": true,
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-5.2.0.tgz",
+      "integrity": "sha512-c18dMeW+PEQdDFzkhDsnBAlS4Z8KGStBQQUcQ5mf7Nf689jyGk0594L+i9RaQuf4gog6SvWLJorz2NfSaqxZ7w==",
       "requires": {
-        "async-limiter": "1.0.0",
-        "safe-buffer": "5.1.1",
-        "ultron": "1.1.1"
+        "async-limiter": "1.0.0"
       }
     },
     "x-is-function": {
diff --git a/package.json b/package.json
index 90dca69e..b927d113 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,7 @@
     "test-integration": "docker-compose up --abort-on-container-exit --exit-code-from integration-tests --build --remove-orphans --quiet-pull && docker-compose down",
     "test-integration-stage": "cross-env BASE_URL=https://send.stage.mozaws.net npm run test-integration",
     "start": "npm run clean && cross-env NODE_ENV=development webpack-dev-server",
-    "prod": "node server/prod.js"
+    "prod": "node server/bin/prod.js"
   },
   "lint-staged": {
     "*.js": [
@@ -82,6 +82,7 @@
     "git-rev-sync": "^1.10.0",
     "github-changes": "^1.1.2",
     "html-loader": "^0.5.5",
+    "http_ece": "^1.0.5",
     "husky": "^0.14.3",
     "lint-staged": "^7.0.0",
     "mocha": "^5.0.4",
@@ -109,6 +110,7 @@
     "svgo-loader": "^2.1.0",
     "testpilot-ga": "^0.3.0",
     "val-loader": "^1.1.0",
+    "web-streams-polyfill": "^1.3.2",
     "webpack": "^3.11.0",
     "webpack-dev-middleware": "^2.0.6",
     "webpack-dev-server": "2.9.1",
@@ -122,13 +124,15 @@
     "cldr-core": "^32.0.0",
     "convict": "^4.0.1",
     "express": "^4.16.2",
+    "express-ws": "^4.0.0",
     "fluent": "^0.6.3",
     "fluent-langneg": "^0.1.0",
     "helmet": "^3.12.0",
     "mkdirp": "^0.5.1",
     "mozlog": "^2.2.0",
     "raven": "^2.4.2",
-    "redis": "^2.8.0"
+    "redis": "^2.8.0",
+    "websocket-stream": "^5.1.2"
   },
   "availableLanguages": [
     "en-US",
diff --git a/server/bin/dev.js b/server/bin/dev.js
new file mode 100644
index 00000000..d94eb8c4
--- /dev/null
+++ b/server/bin/dev.js
@@ -0,0 +1,23 @@
+const assets = require('../../common/assets');
+const locales = require('../../common/locales');
+const routes = require('../routes');
+const pages = require('../routes/pages');
+const tests = require('../../test/frontend/routes');
+const express = require('express');
+const expressWs = require('express-ws');
+const config = require('../config');
+
+const wsapp = express();
+expressWs(wsapp, null, { perMessageDeflate: false });
+wsapp.ws('/api/ws', require('../routes/ws'));
+wsapp.listen(8081, config.listen_address);
+
+module.exports = function(app, devServer) {
+  assets.setMiddleware(devServer.middleware);
+  locales.setMiddleware(devServer.middleware);
+  routes(app);
+  tests(app);
+  // webpack-dev-server routes haven't been added yet
+  // so wait for next tick to add 404 handler
+  process.nextTick(() => app.use(pages.notfound));
+};
diff --git a/server/prod.js b/server/bin/prod.js
similarity index 59%
rename from server/prod.js
rename to server/bin/prod.js
index 4177b160..d52393ed 100644
--- a/server/prod.js
+++ b/server/bin/prod.js
@@ -1,20 +1,22 @@
 const express = require('express');
 const path = require('path');
 const Raven = require('raven');
-const config = require('./config');
-const routes = require('./routes');
-const pages = require('./routes/pages');
+const config = require('../config');
+const routes = require('../routes');
+const pages = require('../routes/pages');
+const expressWs = require('express-ws');
 
 if (config.sentry_dsn) {
   Raven.config(config.sentry_dsn).install();
 }
 
 const app = express();
-
+expressWs(app, null, { perMessageDeflate: false });
+app.ws('/api/ws', require('../routes/ws'));
 routes(app);
 
 app.use(
-  express.static(path.resolve(__dirname, '../dist/'), {
+  express.static(path.resolve(__dirname, '../../dist/'), {
     setHeaders: function(res) {
       res.set('Cache-Control', 'public, max-age=31536000, immutable');
       res.removeHeader('Pragma');
diff --git a/server/bin/test.js b/server/bin/test.js
new file mode 100644
index 00000000..b5f349a5
--- /dev/null
+++ b/server/bin/test.js
@@ -0,0 +1,18 @@
+const assets = require('../../common/assets');
+const locales = require('../../common/locales');
+const routes = require('../routes');
+const pages = require('../routes/pages');
+const tests = require('../../test/frontend/routes');
+const expressWs = require('express-ws');
+
+module.exports = function(app, devServer) {
+  assets.setMiddleware(devServer.middleware);
+  locales.setMiddleware(devServer.middleware);
+  expressWs(app, null, { perMessageDeflate: false });
+  app.ws('/api/ws', require('../routes/ws'));
+  routes(app);
+  tests(app);
+  // webpack-dev-server routes haven't been added yet
+  // so wait for next tick to add 404 handler
+  process.nextTick(() => app.use(pages.notfound));
+};
diff --git a/server/dev.js b/server/dev.js
deleted file mode 100644
index babb9b12..00000000
--- a/server/dev.js
+++ /dev/null
@@ -1,15 +0,0 @@
-const assets = require('../common/assets');
-const locales = require('../common/locales');
-const routes = require('./routes');
-const pages = require('./routes/pages');
-const tests = require('../test/frontend/routes');
-
-module.exports = function(app, devServer) {
-  assets.setMiddleware(devServer.middleware);
-  locales.setMiddleware(devServer.middleware);
-  routes(app);
-  tests(app);
-  // webpack-dev-server routes haven't been added yet
-  // so wait for next tick to add 404 handler
-  process.nextTick(() => app.use(pages.notfound));
-};
diff --git a/server/routes/ws.js b/server/routes/ws.js
new file mode 100644
index 00000000..f2f6250d
--- /dev/null
+++ b/server/routes/ws.js
@@ -0,0 +1,73 @@
+const crypto = require('crypto');
+const storage = require('../storage');
+const config = require('../config');
+const mozlog = require('../log');
+const Limiter = require('../limiter');
+const Parser = require('../streamparser');
+const wsStream = require('websocket-stream/stream');
+
+const log = mozlog('send.upload');
+
+module.exports = async function(ws, req) {
+  let fileStream;
+
+  ws.on('close', e => {
+    if (e !== 1000 && fileStream !== undefined) {
+      fileStream.destroy();
+    }
+  });
+
+  ws.once('message', async function(message) {
+    try {
+      const newId = crypto.randomBytes(5).toString('hex');
+      const owner = crypto.randomBytes(10).toString('hex');
+
+      const fileInfo = JSON.parse(message);
+      const metadata = fileInfo.fileMetadata;
+      const auth = fileInfo.authorization;
+
+      if (!metadata || !auth) {
+        ws.send(
+          JSON.stringify({
+            error: 400
+          })
+        );
+        return ws.close();
+      }
+
+      const meta = {
+        owner,
+        metadata,
+        auth: auth.split(' ')[1],
+        nonce: crypto.randomBytes(16).toString('base64')
+      };
+
+      const protocol = config.env === 'production' ? 'https' : req.protocol;
+      const url = `${protocol}://${req.get('host')}/download/${newId}/`;
+
+      const limiter = new Limiter(config.max_file_size);
+      const parser = new Parser();
+      fileStream = wsStream(ws, { binary: true })
+        .pipe(limiter)
+        .pipe(parser);
+      storage.set(newId, fileStream, meta);
+
+      ws.send(
+        JSON.stringify({
+          url,
+          owner: meta.owner,
+          id: newId,
+          authentication: `send-v1 ${meta.nonce}`
+        })
+      );
+    } catch (e) {
+      log.error('upload', e);
+      ws.send(
+        JSON.stringify({
+          error: e === 'limit' ? 413 : 500
+        })
+      );
+      ws.close();
+    }
+  });
+};
diff --git a/server/streamparser.js b/server/streamparser.js
new file mode 100644
index 00000000..d7f7b110
--- /dev/null
+++ b/server/streamparser.js
@@ -0,0 +1,23 @@
+const { Transform } = require('stream');
+
+class StreamParser extends Transform {
+  constructor() {
+    super();
+    let res;
+    this.promise = new Promise(resolve => {
+      res = resolve;
+    });
+    this.res = res;
+  }
+
+  _transform(chunk, encoding, callback) {
+    if (chunk.byteLength === 1 && chunk[0] === 0) {
+      this.res();
+    } else {
+      this.push(chunk);
+    }
+    callback();
+  }
+}
+
+module.exports = StreamParser;
diff --git a/test/frontend/runner.js b/test/frontend/runner.js
index d474b2d8..3ae95f2f 100644
--- a/test/frontend/runner.js
+++ b/test/frontend/runner.js
@@ -7,7 +7,7 @@ const webpack = require('webpack');
 const config = require('../../webpack.config');
 const middleware = require('webpack-dev-middleware');
 const express = require('express');
-const devRoutes = require('../../server/dev');
+const devRoutes = require('../../server/bin/test');
 const app = express();
 
 const wpm = middleware(webpack(config), { logLevel: 'silent' });
diff --git a/test/frontend/tests/api-tests.js b/test/frontend/tests/api-tests.js
index fb470add..22e221e4 100644
--- a/test/frontend/tests/api-tests.js
+++ b/test/frontend/tests/api-tests.js
@@ -3,21 +3,22 @@ import * as api from '../../../app/api';
 import Keychain from '../../../app/keychain';
 
 const encoder = new TextEncoder();
-const plaintext = encoder.encode('hello world!');
+const plaintext = new Blob([encoder.encode('hello world!')]);
 const metadata = {
   name: 'test.txt',
   type: 'text/plain'
 };
 
 describe('API', function() {
-  describe('uploadFile', function() {
+  describe('websocket upload', function() {
     it('returns file info on success', async function() {
       const keychain = new Keychain();
-      const encrypted = await keychain.encryptFile(plaintext);
+      const enc = keychain.encryptStream(plaintext);
       const meta = await keychain.encryptMetadata(metadata);
       const verifierB64 = await keychain.authKeyB64();
       const p = function() {};
-      const up = api.uploadFile(encrypted, meta, verifierB64, keychain, p);
+      const up = api.uploadWs(enc.stream, enc.streamInfo, meta, verifierB64, p);
+
       const result = await up.result;
       assert.ok(result.url);
       assert.ok(result.id);
@@ -26,11 +27,11 @@ describe('API', function() {
 
     it('can be cancelled', async function() {
       const keychain = new Keychain();
-      const encrypted = await keychain.encryptFile(plaintext);
+      const enc = keychain.encryptStream(plaintext);
       const meta = await keychain.encryptMetadata(metadata);
       const verifierB64 = await keychain.authKeyB64();
       const p = function() {};
-      const up = api.uploadFile(encrypted, meta, verifierB64, keychain, p);
+      const up = api.uploadWs(enc.stream, enc.streamInfo, meta, verifierB64, p);
       up.cancel();
       try {
         await up.result;
diff --git a/test/frontend/tests/streaming-tests.js b/test/frontend/tests/streaming-tests.js
new file mode 100644
index 00000000..355fcaa0
--- /dev/null
+++ b/test/frontend/tests/streaming-tests.js
@@ -0,0 +1,64 @@
+const ece = require('http_ece');
+require('buffer');
+
+import assert from 'assert';
+import { b64ToArray } from '../../../app/utils';
+import ECE from '../../../app/ece.js';
+
+const rs = 36;
+
+const str = 'You are the dancing queen, young and sweet, only seventeen.';
+const testSalt = 'I1BsxtFttlv3u_Oo94xnmw';
+const keystr = 'yqdlZ-tYemfogSmv7Ws5PQ';
+
+const buffer = Buffer.from(str);
+const params = {
+  version: 'aes128gcm',
+  rs: rs,
+  salt: testSalt,
+  keyid: '',
+  key: keystr
+};
+
+const encrypted = ece.encrypt(buffer, params);
+const decrypted = ece.decrypt(encrypted, params);
+
+describe('Streaming', function() {
+  //testing against http_ece's implementation
+  describe('ECE', function() {
+    const key = b64ToArray(keystr);
+    const salt = b64ToArray(testSalt).buffer;
+    const blob = new Blob([str], { type: 'text/plain' });
+
+    it('can encrypt', async function() {
+      const encStream = new ECE(blob, key, 'encrypt', rs, salt).stream;
+      const reader = encStream.getReader();
+
+      let result = Buffer.from([]);
+
+      let state = await reader.read();
+      while (!state.done) {
+        result = Buffer.concat([result, state.value]);
+        state = await reader.read();
+      }
+
+      assert.deepEqual(result, encrypted);
+    });
+
+    it('can decrypt', async function() {
+      const encBlob = new Blob([encrypted]);
+      const decStream = await new ECE(encBlob, key, 'decrypt', rs).stream;
+
+      const reader = decStream.getReader();
+      let result = Buffer.from([]);
+
+      let state = await reader.read();
+      while (!state.done) {
+        result = Buffer.concat([result, state.value]);
+        state = await reader.read();
+      }
+
+      assert.deepEqual(result, decrypted);
+    });
+  });
+});
diff --git a/test/frontend/tests/workflow-tests.js b/test/frontend/tests/workflow-tests.js
index 23bc8efc..eed956da 100644
--- a/test/frontend/tests/workflow-tests.js
+++ b/test/frontend/tests/workflow-tests.js
@@ -93,7 +93,7 @@ describe('Upload / Download flow', function() {
     fs.cancel(); // before encrypting
     try {
       await up;
-      assert.fail('not cancelled');
+      assert.fail('not cancelled 1');
     } catch (e) {
       assert.equal(e.message, '0');
     }
@@ -101,7 +101,7 @@ describe('Upload / Download flow', function() {
     fs.once('encrypting', () => fs.cancel());
     try {
       await fs.upload();
-      assert.fail('not cancelled');
+      assert.fail('not cancelled 2');
     } catch (e) {
       assert.equal(e.message, '0');
     }
@@ -109,7 +109,7 @@ describe('Upload / Download flow', function() {
     fs.once('progress', () => fs.cancel());
     try {
       await fs.upload();
-      assert.fail('not cancelled');
+      assert.fail('not cancelled 3');
     } catch (e) {
       assert.equal(e.message, '0');
     }
diff --git a/webpack.config.js b/webpack.config.js
index 65bc21e0..6619f697 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -209,6 +209,13 @@ module.exports = {
   devServer: {
     compress: true,
     host: '0.0.0.0',
-    before: IS_DEV ? require('./server/dev') : undefined
+    before: IS_DEV ? require('./server/bin/dev') : undefined,
+    proxy: {
+      '/api/ws': {
+        target: 'ws://localhost:8081',
+        ws: true,
+        secure: false
+      }
+    }
   }
 };