---
title: "proxymock: Record, Mock, and Replay Real API Traffic | Speedscale"
description: "Validate AI-generated code with real production traffic before merge using proxymock record, mock, and replay workflows."
canonical: "https://speedscale.com/proxymock/"
---

Free CLI for API mocking and traffic replay

# Record real traffic. Mock dependencies. Replay changes.

Install proxymock and get to your first successful record, mock, or replay workflow in under 10 minutes. Validate AI-generated code with real Traffic Context before merge, without brittle hand-written stubs.

[Install proxymock](https://docs.speedscale.com/proxymock/getting-started/installation) [See 10-minute quickstart](https://speedscale.com/proxymock/#quickstart)

10-minute first success No hand-written stubs Java / .NET / Node.js / Go / Python

```bash
brew install speedscale/tap/proxymock
```

Need team workflows, CI replay, or cloud storage? [Request a demo](https://speedscale.com/company/demo/).

FIRST SUCCESS

```bash
# Install and initialize once
brew install speedscale/tap/proxymock
proxymock init

# Configure outbound proxy settings in the terminal that starts your app.
export http_proxy=http://localhost:4140
export https_proxy=http://localhost:4140
# Start your app on port 8080 with outbound proxy support.
# Record into a fixed directory.
proxymock record --app-port 8080 --out ./proxymock/recorded

# In another terminal, send a real request through the inbound proxy.
curl http://localhost:4143/
# Exercise your API routes, then stop recording with Ctrl-C.

# Start mocks using the captured outbound traffic.
proxymock mock --in ./proxymock/recorded
# Restart your app with http_proxy and https_proxy set to http://localhost:4140.
# Keep the mock running while replaying in another terminal.

# Replay recorded inbound requests and fail on response differences.
proxymock replay --in ./proxymock/recorded \
  --test-against http://localhost:8080 \
  --test-config standard \
  --fail-if 'requests.failed != 0'
```

## Why proxymock?

### Record Real Traffic

Capture Traffic Context, the requests and responses your app actually sees, instead of guessing at response shapes by hand.

### Mock Without Stub Drift

Turn captured traffic into local mocks so your test environment stays aligned with production behavior.

### Replay Changes Before You Ship

Run recorded traffic against local builds or CI jobs to catch regressions with the same requests users already sent.

### Fits Existing Stacks

Use the same record, mock, and replay workflow whether you run Java, .NET, Node.js, or a service in Kubernetes.

### CI-Friendly

Add replay checks to pull requests and give reviewers evidence when a change breaks real request patterns.

### Works for AI Agents Too

The same captured snapshots can be used by Claude Code, Cursor, and Copilot after your core local workflow is working.

## 10-minute quickstart

Start with a running service on port 8080. Configure its outbound proxy using the language guide below. Send requests through port 4143 while recording, then use the captured traffic for mocks and replay.

### 1\. Install

Install the CLI locally with Homebrew and keep the workflow on your machine.

### 2\. Record

Capture one working request flow so the mock data reflects reality.

### 3\. Mock

Run your app with recorded responses instead of live dependencies.

### 4\. Replay

Compare a code change against the same recorded traffic before merge.

### Core workflow

```bash
# Install and initialize once
brew install speedscale/tap/proxymock
proxymock init

# Configure outbound proxy settings in the terminal that starts your app.
export http_proxy=http://localhost:4140
export https_proxy=http://localhost:4140
# Start your app on port 8080 with outbound proxy support.
# Record into a fixed directory.
proxymock record --app-port 8080 --out ./proxymock/recorded

# In another terminal, send a real request through the inbound proxy.
curl http://localhost:4143/
# Exercise your API routes, then stop recording with Ctrl-C.

# Start mocks using the captured outbound traffic.
proxymock mock --in ./proxymock/recorded
# Restart your app with http_proxy and https_proxy set to http://localhost:4140.
# Keep the mock running while replaying in another terminal.

# Replay recorded inbound requests and fail on response differences.
proxymock replay --in ./proxymock/recorded \
  --test-against http://localhost:8080 \
  --test-config standard \
  --fail-if 'requests.failed != 0'
```

Run `proxymock init` once, choose the browser sign-in flow, and keep manual API key copy for CI or headless environments. Use your service’s actual route instead of `/` in the curl example. See the [installation](https://docs.speedscale.com/proxymock/getting-started/installation) docs and the [initialization](https://docs.speedscale.com/proxymock/guides/initialize) guide for the full flow.

### Pick your stack

Each tab opens the docs, shows the matching logo, and links into the demo-app section plus the proxymock workflow.

[View technology support](https://docs.speedscale.com/reference/technology-support/)

Pick your stack

![Java logo](https://speedscale.com/images/logos/languages/java-light.svg) ![Java logo](https://speedscale.com/images/logos/languages/java-dark.svg)

Language guide

### Java

Java demo app command with proxymock proxy environment variables.

Mode: set proxy env vars, then run your app command.

Simple mode Beginner-safe

1\. Set env vars

```bash
export JAVA_TOOL_OPTIONS="$JAVA_TOOL_OPTIONS \
  -Dhttp.proxyHost=127.0.0.1 \
  -Dhttp.proxyPort=4140 \
  -Dhttps.proxyHost=127.0.0.1 \
  -Dhttps.proxyPort=4140"
```

2\. Run app

```bash
./mvnw spring-boot:run
```

[Open guide](https://docs.speedscale.com/reference/languages/java#proxymock)

![.NET logo](https://speedscale.com/images/logos/languages/dotnet-light.png) ![.NET logo](https://speedscale.com/images/logos/languages/dotnet-dark.png)

Language guide

### .NET

ASP.NET Core app command with proxymock proxy environment variables.

Mode: set proxy env vars, then run your app command.

Simple mode Beginner-safe

1\. Set env vars

```bash
export HTTP_PROXY=http://127.0.0.1:4140
export HTTPS_PROXY=http://127.0.0.1:4140
```

2\. Run app

```bash
dotnet run
```

[Open guide](https://docs.speedscale.com/reference/languages/dotnet#proxymock)

![Node.js logo](https://speedscale.com/images/logos/languages/nodejs-light.svg) ![Node.js logo](https://speedscale.com/images/logos/languages/nodejs-dark.svg)

Language guide

### Node.js

Node.js app command with proxymock proxy environment variables.

Mode: set proxy env vars, then run your app command.

Simple mode Beginner-safe

1\. Set env vars

```bash
export HTTP_PROXY=http://127.0.0.1:4140
export HTTPS_PROXY=http://127.0.0.1:4140
```

2\. Run app

```bash
npm start
```

[Open guide](https://docs.speedscale.com/reference/languages/nodejs#proxymock)

![Go logo](https://speedscale.com/images/logos/languages/go-light.svg) ![Go logo](https://speedscale.com/images/logos/languages/go-dark.svg)

Language guide

### Go

Go app command with proxymock proxy environment variables.

Mode: set proxy env vars, then run your app command.

Simple mode Beginner-safe

1\. Set env vars

```bash
export HTTP_PROXY=http://127.0.0.1:4140
export HTTPS_PROXY=http://127.0.0.1:4140
```

2\. Run app

```bash
go run main.go
```

[Open guide](https://docs.speedscale.com/reference/languages/golang#proxymock)

![Python logo](https://speedscale.com/images/logos/languages/python-light.svg) ![Python logo](https://speedscale.com/images/logos/languages/python-dark.svg)

Language guide

### Python

Python app command with proxymock proxy environment variables.

Mode: set proxy env vars, then run your app command.

Simple mode Beginner-safe

1\. Set env vars

```bash
export HTTP_PROXY=http://127.0.0.1:4140
export HTTPS_PROXY=http://127.0.0.1:4140
```

2\. Run app

```bash
python app.py
```

[Open guide](https://docs.speedscale.com/reference/languages/python#proxymock)

## Testing & Mocking

Turn recordings into fast, deterministic tests and use production‑like mocks to develop without external dependencies.

### Run tests

```bash
proxymock replay --test-against localhost:3000 --for 1m --vus 10
```

Regression, contract and load from real traffic, quickly fire it up from your terminal.

### Start mock server

```bash
proxymock mock -- go run main.go
```

Realistic latency and errors; add [transforms](https://docs.speedscale.com/concepts/transforms/) for chaos and data shaping.

## Close the Observability Gap for AI Agents

*   Give Claude Code, Cursor, and Copilot access to real traffic snapshots
    
*   AI agents can replay traffic, inspect responses, and validate changes
    
*   Recorded traffic stays in your local workspace
    

![proxymock MCP integration screenshot](https://speedscale.com/images/screenshots/cursor-proxymock.png)

## AI Code Validation Workflow

From capture to confidence in four steps.

1

### Capture Traffic Context

Record real API calls from staging or production

2

### AI Generates Code

Cursor, Claude, or Copilot writes your changes

3

### Replay & Compare

Validate AI code against captured traffic

4

### Ship with Confidence

Fix regressions before they reach production

![proxymock web showing recorded requests and the details of a selected request](https://speedscale.com/images/screenshots/proxymock-web.png)

## Deep Visibility

*   Browse full call details locally with proxymock web
    
*   See API, gRPC, GraphQL, DB queries, etc.
    
*   Store traffic data as part of the repo
    

## CI Pipeline

Add proxymock to your pipeline to catch issues before deploy. See full examples in our [CI/CD docs](https://docs.speedscale.com/integration/cicd/).

### Start mock server

```bash
proxymock mock \
  --verbose \
  --in $PROXYMOCK_IN_DIR/ \
  --log-to proxymock_mock.log &
```

### Replay and test

```bash
proxymock replay \
  --in "$PROXYMOCK_DIR" \
  --test-against localhost:$APP_PORT \
  --log-to $REPLAY_LOG_FILE \
  --fail-if "latency.max > 1500" \
  -- $APP_COMMAND
```