API Traffic Replay Testing: The Definitive Guide (2026)
What is API traffic replay testing? Capture, sanitize, and replay production traffic. Compare GoReplay vs WireMock vs Speedscale vs proxymock.
Read the guideTraffic replay guides
Traffic replay: test changes against real API behavior
Capture production interactions, remove sensitive data, and replay the same behavior in development, staging, or CI. These guides cover the workflow from first recording to release gate.
Start here
Start with the complete traffic replay guide
Choose what you need to do
Learn how replay works
Understand capture, isolation, replay, and the tradeoffs behind a production-grade system.
Apply it to delivery
Use recorded traffic for debugging, migrations, refactoring, and CI regression tests.
Handle real-world data
Protect sensitive payloads and solve the authentication problems that appear during replay.
All traffic replay articles
Test PostgreSQL With the Queries Your App Actually Runs
Replay recorded PostgreSQL queries to catch schema regressions and run realistic database load tests with proxymock, using the CLI or an AI assistant.
Use AI and traffic replay to test AI-generated code
Have your coding agent test AI-generated code with proxymock: capture working API traffic, replay it against changes, and inspect the results.
Synthetic Monitoring Is Broken. Your Production Traffic Can Fix It.
Synthetic monitoring depends on scripts engineers maintain by hand. Capturing and replaying real production transactions turns customer behavior into tests.
Capture once, test forever
Production traffic is the most complete record of what your system does, and most teams throw it away. One capture powers reproduce, validate, and sandbox.
The DIY Traffic Replay Trap: Why AI Scripts Fail at Scale
AI-generated scripts seem like a quick win, but DIY traffic replay tools become a maintenance nightmare at scale. Here's why Speedscale beats the prompt.
Replace API Synthetics with Traffic Replay
UI synthetics only tell you something is broken. Traffic replay per microservice isolates failures before any human walks up. Zero scripts required.
Oracle JDK to OpenJDK: A Guide to Reliable Migration Testing
Record production traffic on Oracle JDK, replay it on OpenJDK, and catch every regression before users do. A step-by-step Speedscale guide.
Part 2: Building a Production-Grade Traffic Capture, Transform and Replay System
Learn how to build a traffic analysis tool for network traffic transformation. Complete guide covering traffic analysis techniques, parsing.
Part 1: Building a Production-Grade Traffic Capture and Replay System
Learn how to build a production-grade traffic capture system using proxies, eBPF, and tcpdump.
Replay real traffic before release
Turn production API behavior into repeatable tests without writing every scenario by hand.