diff --git a/.tool-versions b/.tool-versions
new file mode 100644
index 000000000..d7568adf6
--- /dev/null
+++ b/.tool-versions
@@ -0,0 +1 @@
+nodejs 20.11.1
diff --git a/jest.config.js b/jest.config.js
index 228ed1f67..19fd30d22 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -46,11 +46,15 @@ module.exports = {
     {
       displayName: 'delivery-fetch',
       testMatch: ['<rootDir>/packages/delivery-fetch/**/*.test.ts'],
+      testEnvironment: 'jsdom',
+      setupFilesAfterEnv: ['<rootDir>/jest/setup/crypto.ts'],
       ...defaultModuleConfig
     },
     {
       displayName: 'browser',
       testMatch: ['<rootDir>/packages/platforms/browser/**/*.test.ts'],
+      testEnvironment: 'jsdom',
+      setupFilesAfterEnv: ['<rootDir>/jest/setup/crypto.ts'],
       ...defaultModuleConfig
     },
     {
diff --git a/jest/setup/crypto.ts b/jest/setup/crypto.ts
new file mode 100644
index 000000000..659f09583
--- /dev/null
+++ b/jest/setup/crypto.ts
@@ -0,0 +1,19 @@
+import { TextDecoder, TextEncoder } from 'node:util'
+import crypto from 'crypto'
+
+Object.defineProperty(window, 'crypto', {
+  get () {
+    return {
+      getRandomValues: crypto.getRandomValues,
+      subtle: crypto.webcrypto.subtle
+    }
+  }
+})
+
+Object.defineProperty(window, 'TextEncoder', {
+  get () { return TextEncoder }
+})
+
+Object.defineProperty(window, 'TextDecoder', {
+  get () { return TextDecoder }
+})
diff --git a/packages/core/lib/config.ts b/packages/core/lib/config.ts
index ebf3abca7..a6fd24de5 100644
--- a/packages/core/lib/config.ts
+++ b/packages/core/lib/config.ts
@@ -8,7 +8,7 @@ import {
   ATTRIBUTE_STRING_VALUE_LIMIT_MAX
 } from './custom-attribute-limits'
 import type { Plugin } from './plugin'
-import { isLogger, isNumber, isObject, isOnSpanEndCallbacks, isPluginArray, isString, isStringArray, isStringWithLength } from './validation'
+import { isBoolean, isLogger, isNumber, isObject, isOnSpanEndCallbacks, isPluginArray, isString, isStringArray, isStringWithLength } from './validation'
 
 type SetTraceCorrelation = (traceId: string, spanId: string) => void
 
@@ -53,6 +53,7 @@ export interface Configuration {
   attributeStringValueLimit?: number
   attributeArrayLengthLimit?: number
   attributeCountLimit?: number
+  sendPayloadChecksums?: boolean
 }
 
 export interface TestConfiguration {
@@ -81,6 +82,7 @@ export interface CoreSchema extends Schema {
   plugins: ConfigOption<Array<Plugin<Configuration>>>
   bugsnag: ConfigOption<BugsnagErrorStatic | undefined>
   samplingProbability: ConfigOption<number | undefined>
+  sendPayloadChecksums: ConfigOption<boolean>
 }
 
 export const schema: CoreSchema = {
@@ -153,6 +155,11 @@ export const schema: CoreSchema = {
     defaultValue: ATTRIBUTE_COUNT_LIMIT_DEFAULT,
     message: `should be a number between 1 and ${ATTRIBUTE_COUNT_LIMIT_MAX}`,
     validate: (value: unknown): value is number => isNumber(value) && value > 0 && value <= ATTRIBUTE_COUNT_LIMIT_MAX
+  },
+  sendPayloadChecksums: {
+    defaultValue: false,
+    message: 'should be true|false',
+    validate: isBoolean
   }
 }
 
diff --git a/packages/core/lib/core.ts b/packages/core/lib/core.ts
index f259e35ea..215618e5a 100644
--- a/packages/core/lib/core.ts
+++ b/packages/core/lib/core.ts
@@ -73,6 +73,11 @@ export function createClient<S extends CoreSchema, C extends Configuration, T> (
     start: (config: C | string) => {
       const configuration = validateConfig<S, C>(config, options.schema)
 
+      // sendPayloadChecksums is false by default unless custom endpoints are not specified
+      if (typeof config !== 'string' && !config.endpoint) {
+        configuration.sendPayloadChecksums = ('sendPayloadChecksums' in config && config.sendPayloadChecksums) || true
+      }
+
       // if using the default endpoint add the API key as a subdomain
       // e.g. convert URL https://otlp.bugsnag.com/v1/traces to URL https://<project_api_key>.otlp.bugsnag.com/v1/traces
       if (configuration.endpoint === schema.endpoint.defaultValue) {
@@ -92,7 +97,7 @@ export function createClient<S extends CoreSchema, C extends Configuration, T> (
         }
       }
 
-      const delivery = options.deliveryFactory(configuration.endpoint)
+      const delivery = options.deliveryFactory(configuration.endpoint, configuration.sendPayloadChecksums)
 
       options.spanAttributesSource.configure(configuration)
 
diff --git a/packages/core/lib/delivery.ts b/packages/core/lib/delivery.ts
index 1bdecf39d..036f4a25a 100644
--- a/packages/core/lib/delivery.ts
+++ b/packages/core/lib/delivery.ts
@@ -5,7 +5,7 @@ import type { JsonEvent } from './events'
 import type { Kind, SpanEnded } from './span'
 import { spanToJson } from './span'
 
-export type DeliveryFactory = (endpoint: string) => Delivery
+export type DeliveryFactory = (endpoint: string, sendPayloadChecksums: boolean) => Delivery
 
 export type ResponseState = 'success' | 'failure-discard' | 'failure-retryable'
 
@@ -60,6 +60,8 @@ export interface TracePayload {
     // therefore it's 'undefined' when passed to delivery, which adds a value
     // immediately before initiating the request
     'Bugsnag-Sent-At'?: string
+    // 'undefined' when passed to delivery, which adds a value before initiating the request
+    'Bugsnag-Integrity'?: string
   }
 }
 
diff --git a/packages/core/tests/core.test.ts b/packages/core/tests/core.test.ts
index 258c915ae..3a20d196c 100644
--- a/packages/core/tests/core.test.ts
+++ b/packages/core/tests/core.test.ts
@@ -342,7 +342,7 @@ describe('Core', () => {
 
               await jest.runOnlyPendingTimersAsync()
 
-              expect(deliveryFactory).toHaveBeenCalledWith('https://a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6.otlp.bugsnag.com/v1/traces')
+              expect(deliveryFactory).toHaveBeenCalledWith('https://a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6.otlp.bugsnag.com/v1/traces', false)
             })
           })
 
@@ -356,7 +356,7 @@ describe('Core', () => {
 
               await jest.runOnlyPendingTimersAsync()
 
-              expect(deliveryFactory).toHaveBeenCalledWith('https://my-custom-otel-repeater.com')
+              expect(deliveryFactory).toHaveBeenCalledWith('https://my-custom-otel-repeater.com', false)
             })
           })
         })
diff --git a/packages/delivery-fetch/lib/delivery.ts b/packages/delivery-fetch/lib/delivery.ts
index 69a638b27..600ac3b11 100644
--- a/packages/delivery-fetch/lib/delivery.ts
+++ b/packages/delivery-fetch/lib/delivery.ts
@@ -1,7 +1,4 @@
-import {
-
-  responseStateFromStatusCode
-} from '@bugsnag/core-performance'
+import { responseStateFromStatusCode } from '@bugsnag/core-performance'
 import type { BackgroundingListener, Clock, Delivery, DeliveryFactory, TracePayload } from '@bugsnag/core-performance'
 
 export type Fetch = typeof fetch
@@ -40,7 +37,7 @@ function createFetchDeliveryFactory (
     })
   }
 
-  return function fetchDeliveryFactory (endpoint: string): Delivery {
+  return function fetchDeliveryFactory (endpoint: string, sendPayloadChecksums?: boolean): Delivery {
     return {
       async send (payload: TracePayload) {
         const body = JSON.stringify(payload.body)
@@ -48,6 +45,12 @@ function createFetchDeliveryFactory (
         payload.headers['Bugsnag-Sent-At'] = clock.date().toISOString()
 
         try {
+          const integrityHeaderValue = await getIntegrityHeaderValue(sendPayloadChecksums ?? false, window, body)
+
+          if (integrityHeaderValue) {
+            payload.headers['Bugsnag-Integrity'] = integrityHeaderValue
+          }
+
           const response = await fetch(endpoint, {
             method: 'POST',
             keepalive,
@@ -72,3 +75,19 @@ function createFetchDeliveryFactory (
 }
 
 export default createFetchDeliveryFactory
+
+function getIntegrityHeaderValue (sendPayloadChecksums: boolean, windowOrWorkerGlobalScope: Window, requestBody: string) {
+  if (sendPayloadChecksums && windowOrWorkerGlobalScope.isSecureContext && windowOrWorkerGlobalScope.crypto && windowOrWorkerGlobalScope.crypto.subtle && windowOrWorkerGlobalScope.crypto.subtle.digest && typeof TextEncoder === 'function') {
+    const msgUint8 = new TextEncoder().encode(requestBody)
+    return windowOrWorkerGlobalScope.crypto.subtle.digest('SHA-1', msgUint8).then((hashBuffer) => {
+      const hashArray = Array.from(new Uint8Array(hashBuffer))
+      const hashHex = hashArray
+        .map((b) => b.toString(16).padStart(2, '0'))
+        .join('')
+
+      return 'sha1 ' + hashHex
+    })
+  }
+
+  return Promise.resolve()
+}
diff --git a/packages/delivery-fetch/tests/delivery.test.ts b/packages/delivery-fetch/tests/delivery.test.ts
index be8e64687..89a37e709 100644
--- a/packages/delivery-fetch/tests/delivery.test.ts
+++ b/packages/delivery-fetch/tests/delivery.test.ts
@@ -1,7 +1,3 @@
-/**
- * @jest-environment jsdom
- */
-
 import type { TracePayload } from '@bugsnag/core-performance'
 import type { JsonEvent } from '@bugsnag/core-performance/lib'
 import {
@@ -14,11 +10,15 @@ import createFetchDeliveryFactory from '../lib/delivery'
 const SENT_AT_FORMAT = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}Z$/
 
 describe('Browser Delivery', () => {
-  it('delivers a span', async () => {
-    const fetch = jest.fn(() => Promise.resolve({ status: 200, headers: new Headers() } as unknown as Response))
-    const backgroundingListener = new ControllableBackgroundingListener()
-    const clock = new IncrementingClock('2023-01-02T00:00:00.000Z')
+  beforeAll(() => {
+    window.isSecureContext = true
+  })
+
+  afterAll(() => {
+    window.isSecureContext = false
+  })
 
+  it('delivers a span', async () => {
     const deliveryPayload: TracePayload = {
       body: {
         resourceSpans: [{
@@ -45,8 +45,12 @@ describe('Browser Delivery', () => {
       }
     }
 
+    const fetch = jest.fn(() => Promise.resolve({ status: 200, headers: new Headers() } as unknown as Response))
+    const backgroundingListener = new ControllableBackgroundingListener()
+    const clock = new IncrementingClock('2023-01-02T00:00:00.000Z')
+
     const deliveryFactory = createFetchDeliveryFactory(fetch, clock, backgroundingListener)
-    const delivery = deliveryFactory('/test')
+    const delivery = deliveryFactory('/test', true)
     const response = await delivery.send(deliveryPayload)
 
     expect(fetch).toHaveBeenCalledWith('/test', {
@@ -57,7 +61,8 @@ describe('Browser Delivery', () => {
         'Bugsnag-Api-Key': 'test-api-key',
         'Bugsnag-Span-Sampling': '1:1',
         'Content-Type': 'application/json',
-        'Bugsnag-Sent-At': new Date(clock.timeOrigin + 1).toISOString()
+        'Bugsnag-Sent-At': new Date(clock.timeOrigin + 1).toISOString(),
+        'Bugsnag-Integrity': 'sha1 835f1ff603eb1be3bf91fc9716c0841e1b37ee64'
       }
     })
 
@@ -98,7 +103,7 @@ describe('Browser Delivery', () => {
     }
 
     const deliveryFactory = createFetchDeliveryFactory(fetch, new IncrementingClock(), backgroundingListener)
-    const delivery = deliveryFactory('/test')
+    const delivery = deliveryFactory('/test', false)
 
     backgroundingListener.sendToBackground()
 
@@ -153,7 +158,7 @@ describe('Browser Delivery', () => {
     }
 
     const deliveryFactory = createFetchDeliveryFactory(fetch, new IncrementingClock(), backgroundingListener)
-    const delivery = deliveryFactory('/test')
+    const delivery = deliveryFactory('/test', false)
 
     backgroundingListener.sendToBackground()
     backgroundingListener.sendToForeground()
@@ -200,7 +205,7 @@ describe('Browser Delivery', () => {
     const backgroundingListener = new ControllableBackgroundingListener()
 
     const deliveryFactory = createFetchDeliveryFactory(fetch, new IncrementingClock(), backgroundingListener)
-    const delivery = deliveryFactory('/test')
+    const delivery = deliveryFactory('/test', false)
     const deliveryPayload: TracePayload = {
       body: { resourceSpans: [] },
       headers: {
@@ -238,7 +243,7 @@ describe('Browser Delivery', () => {
     const backgroundingListener = new ControllableBackgroundingListener()
 
     const deliveryFactory = createFetchDeliveryFactory(fetch, new IncrementingClock(), backgroundingListener)
-    const delivery = deliveryFactory('/test')
+    const delivery = deliveryFactory('/test', false)
     const payload: TracePayload = {
       body: { resourceSpans: [] },
       headers: {
@@ -293,10 +298,119 @@ describe('Browser Delivery', () => {
     }
 
     const deliveryFactory = createFetchDeliveryFactory(fetch, clock, backgroundingListener)
-    const delivery = deliveryFactory('/test')
+    const delivery = deliveryFactory('/test', false)
 
     const { state } = await delivery.send(deliveryPayload)
 
     expect(state).toBe('failure-discard')
   })
+
+  it('omits the bugsnag integrity header when not in a secure context', async () => {
+    const deliveryPayload: TracePayload = {
+      body: {
+        resourceSpans: [{
+          resource: { attributes: [{ key: 'test-key', value: { stringValue: 'test-value' } }] },
+          scopeSpans: [{
+            spans: [{
+              name: 'test-span',
+              kind: 1,
+              spanId: 'test-span-id',
+              traceId: 'test-trace-id',
+              endTimeUnixNano: '56789',
+              startTimeUnixNano: '12345',
+              attributes: [{ key: 'test-span', value: { intValue: '12345' } }],
+              droppedAttributesCount: 0,
+              events: []
+            }]
+          }]
+        }]
+      },
+      headers: {
+        'Bugsnag-Api-Key': 'test-api-key',
+        'Content-Type': 'application/json',
+        'Bugsnag-Span-Sampling': '1:1'
+      }
+    }
+
+    window.isSecureContext = false
+    const _fetch = jest.fn(() => Promise.resolve({ status: 200, headers: new Headers() } as unknown as Response))
+    const backgroundingListener = new ControllableBackgroundingListener()
+    const clock = new IncrementingClock('2023-01-02T00:00:00.000Z')
+
+    const deliveryFactory = createFetchDeliveryFactory(_fetch, clock, backgroundingListener)
+    const delivery = deliveryFactory('/test', true)
+    const response = await delivery.send(deliveryPayload)
+
+    expect(_fetch).toHaveBeenCalledWith('/test', {
+      method: 'POST',
+      keepalive: false,
+      body: JSON.stringify(deliveryPayload.body),
+      headers: {
+        'Bugsnag-Api-Key': 'test-api-key',
+        'Bugsnag-Span-Sampling': '1:1',
+        'Content-Type': 'application/json',
+        'Bugsnag-Sent-At': new Date(clock.timeOrigin + 1).toISOString()
+      }
+    })
+
+    expect(response).toStrictEqual({
+      state: 'success',
+      samplingProbability: undefined
+    })
+
+    window.isSecureContext = true
+  })
+
+  it('omits the bugsnag integrity header when sendPayloadChecksums is false', async () => {
+    const deliveryPayload: TracePayload = {
+      body: {
+        resourceSpans: [{
+          resource: { attributes: [{ key: 'test-key', value: { stringValue: 'test-value' } }] },
+          scopeSpans: [{
+            spans: [{
+              name: 'test-span',
+              kind: 1,
+              spanId: 'test-span-id',
+              traceId: 'test-trace-id',
+              endTimeUnixNano: '56789',
+              startTimeUnixNano: '12345',
+              attributes: [{ key: 'test-span', value: { intValue: '12345' } }],
+              droppedAttributesCount: 0,
+              events: []
+            }]
+          }]
+        }]
+      },
+      headers: {
+        'Bugsnag-Api-Key': 'test-api-key',
+        'Content-Type': 'application/json',
+        'Bugsnag-Span-Sampling': '1:1'
+      }
+    }
+
+    const fetch = jest.fn(() => Promise.resolve({ status: 200, headers: new Headers() } as unknown as Response))
+    const backgroundingListener = new ControllableBackgroundingListener()
+    const clock = new IncrementingClock('2023-01-02T00:00:00.000Z')
+
+    const deliveryFactory = createFetchDeliveryFactory(fetch, clock, backgroundingListener)
+    const delivery = deliveryFactory('/test', false)
+    const response = await delivery.send(deliveryPayload)
+
+    expect(fetch).toHaveBeenCalledWith('/test', {
+      method: 'POST',
+      keepalive: false,
+      body: JSON.stringify(deliveryPayload.body),
+      headers: {
+        'Bugsnag-Api-Key': 'test-api-key',
+        'Bugsnag-Span-Sampling': '1:1',
+        'Content-Type': 'application/json',
+        'Bugsnag-Sent-At': new Date(clock.timeOrigin + 1).toISOString()
+      }
+    })
+
+    expect(response).toStrictEqual({
+      state: 'success',
+      samplingProbability: undefined
+    })
+  })
 })
diff --git a/packages/platforms/browser/tests/browser.test.ts b/packages/platforms/browser/tests/browser.test.ts
index 8deab3243..502fbf193 100644
--- a/packages/platforms/browser/tests/browser.test.ts
+++ b/packages/platforms/browser/tests/browser.test.ts
@@ -319,4 +319,73 @@ describe('Browser client integration tests', () => {
       await jest.runOnlyPendingTimersAsync()
     })
   })
+
+  describe('payload checksum behavior (Bugsnag-Integrity header)', () => {
+    beforeAll(() => {
+      // eslint-disable-next-line compat/compat
+      window.isSecureContext = true
+    })
+
+    afterAll(() => {
+      // eslint-disable-next-line compat/compat
+      window.isSecureContext = false
+    })
+
+    it('includes the integrity header by default', async () => {
+      client.start({
+        apiKey: VALID_API_KEY,
+        autoInstrumentFullPageLoads: false,
+        autoInstrumentNetworkRequests: false,
+        autoInstrumentRouteChanges: false
+      })
+
+      setNextSamplingProbability(0.2)
+      createSpans(100)
+      await jest.advanceTimersByTimeAsync(RESPONSE_TIME + 1)
+      expect(mockFetch).toHaveBeenCalledTimes(2)
+
+      expect(mockFetch.mock.calls[1][1]).toEqual(expect.objectContaining({
+        headers: expect.objectContaining({ 'Bugsnag-Integrity': expect.stringMatching(/^sha1 (\d|[abcdef]){40}$/) })
+      }))
+    })
+
+    it('does not include the integrity header if endpoint configuration is supplied', async () => {
+      client.start({
+        apiKey: VALID_API_KEY,
+        endpoint: '/test',
+        autoInstrumentFullPageLoads: false,
+        autoInstrumentNetworkRequests: false,
+        autoInstrumentRouteChanges: false
+      })
+
+      setNextSamplingProbability(0.2)
+      createSpans(100)
+      await jest.advanceTimersByTimeAsync(RESPONSE_TIME + 1)
+      expect(mockFetch).toHaveBeenCalledTimes(2)
+
+      expect(mockFetch.mock.calls[1][1]).toEqual(expect.objectContaining({
+        headers: expect.not.objectContaining({ 'Bugsnag-Integrity': expect.any(String) })
+      }))
+    })
+
+    it('can be enabled for a custom endpoint configuration by using sendPayloadChecksums', async () => {
+      client.start({
+        apiKey: VALID_API_KEY,
+        endpoint: '/test',
+        sendPayloadChecksums: true,
+        autoInstrumentFullPageLoads: false,
+        autoInstrumentNetworkRequests: false,
+        autoInstrumentRouteChanges: false
+      })
+
+      setNextSamplingProbability(0.2)
+      createSpans(100)
+      await jest.advanceTimersByTimeAsync(RESPONSE_TIME + 1)
+      expect(mockFetch).toHaveBeenCalledTimes(2)
+
+      expect(mockFetch.mock.calls[1][1]).toEqual(expect.objectContaining({
+        headers: expect.objectContaining({ 'Bugsnag-Integrity': expect.stringMatching(/^sha1 (\d|[abcdef]){40}$/) })
+      }))
+    })
+  })
 })
diff --git a/test/browser/features/fixtures/packages/integrity-disabled/index.html b/test/browser/features/fixtures/packages/integrity-disabled/index.html
new file mode 100644
index 000000000..65e6364f8
--- /dev/null
+++ b/test/browser/features/fixtures/packages/integrity-disabled/index.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <meta charset="utf-8" />
+        <link href="/favicon.png" rel="shortcut icon" type="image/x-icon">
+        <script src="./dist/bundle.js" type="module"></script>
+        <title>Integrity header</title>
+    </head>
+    <body>
+        <h1>integrity-header</h1>
+        <button id="send-span">send-span</button>
+    </body>
+</html>
diff --git a/test/browser/features/fixtures/packages/integrity-disabled/package.json b/test/browser/features/fixtures/packages/integrity-disabled/package.json
new file mode 100644
index 000000000..62faf341f
--- /dev/null
+++ b/test/browser/features/fixtures/packages/integrity-disabled/package.json
@@ -0,0 +1,8 @@
+{
+    "name": "integrity-disabled",
+    "private": true,
+    "scripts": {
+        "build": "rollup --config ../rollup.config.mjs",
+        "clean": "rm -rf dist"
+    }
+}
diff --git a/test/browser/features/fixtures/packages/integrity-disabled/src/index.js b/test/browser/features/fixtures/packages/integrity-disabled/src/index.js
new file mode 100644
index 000000000..13a2f8c8a
--- /dev/null
+++ b/test/browser/features/fixtures/packages/integrity-disabled/src/index.js
@@ -0,0 +1,28 @@
+import BugsnagPerformance from '@bugsnag/browser-performance'
+
+const parameters = new URLSearchParams(window.location.search)
+const apiKey = parameters.get('api_key')
+const endpoint = parameters.get('endpoint')
+
+BugsnagPerformance.start({
+  apiKey,
+  endpoint,
+  sendPayloadChecksums: false,
+  maximumBatchSize: 1,
+  autoInstrumentFullPageLoads: false,
+  autoInstrumentNetworkRequests: false,
+  autoInstrumentRouteChanges: false,
+  serviceName: 'integrity'
+})
+
+document.getElementById('send-span').onclick = () => {
+  const spanOptions = {}
+  
+  if (parameters.has('isFirstClass')) {
+    spanOptions.isFirstClass = JSON.parse(parameters.get('isFirstClass'))
+  }
+
+  const span = BugsnagPerformance.startSpan("Custom/ManualSpanScenario", spanOptions)
+  span.end()
+}
+
diff --git a/test/browser/features/fixtures/packages/integrity/index.html b/test/browser/features/fixtures/packages/integrity/index.html
new file mode 100644
index 000000000..65e6364f8
--- /dev/null
+++ b/test/browser/features/fixtures/packages/integrity/index.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <meta charset="utf-8" />
+        <link href="/favicon.png" rel="shortcut icon" type="image/x-icon">
+        <script src="./dist/bundle.js" type="module"></script>
+        <title>Integrity header</title>
+    </head>
+    <body>
+        <h1>integrity-header</h1>
+        <button id="send-span">send-span</button>
+    </body>
+</html>
diff --git a/test/browser/features/fixtures/packages/integrity/package.json b/test/browser/features/fixtures/packages/integrity/package.json
new file mode 100644
index 000000000..2c29397f5
--- /dev/null
+++ b/test/browser/features/fixtures/packages/integrity/package.json
@@ -0,0 +1,8 @@
+{
+    "name": "integrity",
+    "private": true,
+    "scripts": {
+        "build": "rollup --config ../rollup.config.mjs",
+        "clean": "rm -rf dist"
+    }
+}
diff --git a/test/browser/features/fixtures/packages/integrity/src/index.js b/test/browser/features/fixtures/packages/integrity/src/index.js
new file mode 100644
index 000000000..dab93ae96
--- /dev/null
+++ b/test/browser/features/fixtures/packages/integrity/src/index.js
@@ -0,0 +1,28 @@
+import BugsnagPerformance from '@bugsnag/browser-performance'
+
+const parameters = new URLSearchParams(window.location.search)
+const apiKey = parameters.get('api_key')
+const endpoint = parameters.get('endpoint')
+
+BugsnagPerformance.start({
+  apiKey,
+  endpoint,
+  sendPayloadChecksums: true,
+  maximumBatchSize: 1,
+  autoInstrumentFullPageLoads: false,
+  autoInstrumentNetworkRequests: false,
+  autoInstrumentRouteChanges: false,
+  serviceName: 'integrity'
+})
+
+document.getElementById('send-span').onclick = () => {
+  const spanOptions = {}
+  
+  if (parameters.has('isFirstClass')) {
+    spanOptions.isFirstClass = JSON.parse(parameters.get('isFirstClass'))
+  }
+
+  const span = BugsnagPerformance.startSpan("Custom/ManualSpanScenario", spanOptions)
+  span.end()
+}
+
diff --git a/test/browser/features/integrity.feature b/test/browser/features/integrity.feature
new file mode 100644
index 000000000..8cca1ec94
--- /dev/null
+++ b/test/browser/features/integrity.feature
@@ -0,0 +1,20 @@
+@skip_safari_11
+Feature: Integrity header
+
+Scenario: Integrity headers are set when setPayloadChecksums is true
+  Given I navigate to the test URL "/docs/integrity"
+  And I wait to receive a sampling request
+  Then I click the element "send-span"
+  And I wait for 1 span
+
+  Then the sampling request "bugsnag-integrity" header matches the regex "^sha1 (\d|[abcdef]){40}$"
+  Then the trace "bugsnag-integrity" header matches the regex "^sha1 (\d|[abcdef]){40}$"
+
+Scenario: Integrity headers are not set when setPayloadChecksums is false
+  Given I navigate to the test URL "/docs/integrity-disabled"
+  And I wait to receive a sampling request
+  Then I click the element "send-span"
+  And I wait for 1 span
+
+  Then the sampling request "bugsnag-integrity" header is not present
+  Then the trace "bugsnag-integrity" header is not present
\ No newline at end of file
diff --git a/test/browser/features/support/maze-config.rb b/test/browser/features/support/maze-config.rb
index a15b30b7b..c78fd19d9 100644
--- a/test/browser/features/support/maze-config.rb
+++ b/test/browser/features/support/maze-config.rb
@@ -16,11 +16,7 @@ def get_test_url()
     maze_address = "#{host}:9339"
   end
 
-  if Maze.config.https
-    protocol = 'https'
-  else
-    protocol = 'http'
-  end
+  protocol = Maze.config.https ? 'https' : 'http'
 
   UrlGenerator.new(
     URI("#{protocol}://#{maze_address}"),