diff --git a/.gitignore b/.gitignore
index cfe66ee..2395f73 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@ lib
 .npmrc
 .vscode
 *.tgz
-.tmp
\ No newline at end of file
+.tmp
+*.log
\ No newline at end of file
diff --git a/package.json b/package.json
index cf466e1..fd400b1 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,9 @@
     "pretest": "node_modules/.bin/tsc",
     "test": "mocha .tmp/spec/index.spec.js",
     "posttest": "npm run lint && rm -rf .tmp",
+    "preintegrationTest": "node_modules/.bin/tsc",
+    "integrationTest": "firebase emulators:exec --project=not-a-project --only firestore 'mocha .tmp/spec/integration/**/*.spec.js'",
+    "postintegrationTest": "rm -rf .tmp",
     "format": "prettier --check '**/*.{json,ts,yml,yaml}'",
     "format:fix": "prettier --write '**/*.{json,ts,yml,yaml}'"
   },
@@ -44,6 +47,7 @@
     "chai": "^4.2.0",
     "firebase-admin": "~8.9.0",
     "firebase-functions": "^3.3.0",
+    "firebase-tools": "^8.9.2",
     "mocha": "^6.2.2",
     "prettier": "^1.19.1",
     "sinon": "^7.5.0",
diff --git a/spec/integration/providers/firestore.spec.ts b/spec/integration/providers/firestore.spec.ts
new file mode 100644
index 0000000..406e84f
--- /dev/null
+++ b/spec/integration/providers/firestore.spec.ts
@@ -0,0 +1,44 @@
+import { expect } from 'chai';
+import { firestore, initializeApp } from 'firebase-admin';
+import fft = require('../../../src/index');
+
+describe('providers/firestore', () => {
+  before(() => {
+    initializeApp();
+  });
+
+  it('clears database with clearFirestoreData', async () => {
+    const test = fft({ projectId: 'not-a-project' });
+    const db = firestore();
+
+    await Promise.all([
+      db
+        .collection('test')
+        .doc('doc1')
+        .set({}),
+      db
+        .collection('test')
+        .doc('doc1')
+        .collection('test')
+        .doc('doc2')
+        .set({}),
+    ]);
+
+    await test.firestore.clearFirestoreData({ projectId: 'not-a-project' });
+
+    const docs = await Promise.all([
+      db
+        .collection('test')
+        .doc('doc1')
+        .get(),
+      db
+        .collection('test')
+        .doc('doc1')
+        .collection('test')
+        .doc('doc2')
+        .get(),
+    ]);
+    expect(docs[0].exists).to.be.false;
+    expect(docs[1].exists).to.be.false;
+  });
+});
diff --git a/src/providers/firestore.ts b/src/providers/firestore.ts
index 42944c4..b584461 100644
--- a/src/providers/firestore.ts
+++ b/src/providers/firestore.ts
@@ -27,6 +27,8 @@ import { has, get, isEmpty, isPlainObject, mapValues } from 'lodash';
 
 import { testApp } from '../app';
 
+import * as http from 'http';
+
 /** Optional parameters for creating a DocumentSnapshot. */
 export interface DocumentSnapshotOptions {
   /** ISO timestamp string for the snapshot was read, default is current time.  */
@@ -214,3 +216,58 @@ export function objectToValueProto(data: object) {
 
   return mapValues(data, encodeHelper);
 }
+
+const FIRESTORE_ADDRESS_ENVS = [
+  'FIRESTORE_EMULATOR_HOST',
+  'FIREBASE_FIRESTORE_EMULATOR_ADDRESS',
+];
+
+const FIRESTORE_ADDRESS = FIRESTORE_ADDRESS_ENVS.reduce(
+  (addr, name) => process.env[name] || addr,
+  'localhost:8080'
+);
+const FIRESTORE_PORT = FIRESTORE_ADDRESS.split(':')[1];
+
+/** Clears all data in firestore. Works only in offline mode.
+ */
+export function clearFirestoreData(options: { projectId: string } | string) {
+  return new Promise((resolve, reject) => {
+    let projectId;
+
+    if (typeof options === 'string') {
+      projectId = options;
+    } else if (typeof options === 'object' && has(options, 'projectId')) {
+      projectId = options.projectId;
+    } else {
+      throw new Error('projectId not specified');
+    }
+
+    const config = {
+      method: 'DELETE',
+      hostname: 'localhost',
+      port: FIRESTORE_PORT,
+      path: `/emulator/v1/projects/${projectId}/databases/(default)/documents`,
+    };
+
+    const req = http.request(config, (res) => {
+      if (res.statusCode !== 200) {
+        reject(new Error(`statusCode: ${res.statusCode}`));
+      }
+      res.on('data', () => {});
+      res.on('end', resolve);
+    });
+
+    req.on('error', (error) => {
+      reject(error);
+    });
+
+    const postData = JSON.stringify({
+      database: `projects/${projectId}/databases/(default)`,
+    });
+
+    req.setHeader('Content-Length', postData.length);
+
+    req.write(postData);
+    req.end();
+  });
+}