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go-vcr is a Go testing library that records HTTP interactions during test runs and replays them in future runs, eliminating external API dependencies and making tests faster and deterministic. It provides hooks for sanitizing sensitive data before storage and supports custom request matching strategies.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | dnaeon/go-vcr |
| Owner | dnaeon |
| Primary language | Go |
| License | BSD-2-Clause — OSI-approved |
| Stars | 1.4k |
| Forks | 80 |
| Open issues | 5 |
| Latest release | v4.0.7 (2026-06-25) |
| Last updated | 2026-06-25 |
| Source | https://github.com/dnaeon/go-vcr |
What go-vcr is
go-vcr wraps the Go HTTP client to intercept and record request/response pairs as YAML cassettes. It operates in record and replay modes, with extensibility via hooks (AfterCaptureHook, BeforeSaveHook, BeforeResponseReplayHook), custom matchers, and passthrough handlers for bypassing recording on specific requests.
Get the go-vcr source
Clone the repository and explore it locally.
git clone https://github.com/dnaeon/go-vcr.gitcd go-vcr# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Cassette files (YAML) must be committed to version control and kept in sync when APIs change; plan a process for cassette rotation and invalidation.
- Use BeforeSaveHook to redact secrets before persistence; AfterCaptureHook modifies in-memory state and may affect subsequent test requests.
- Custom matchers are essential for non-trivial request bodies (JSON payloads, form data); the default matcher handles method, URL, and simple matching.
- Passthrough handlers allow specific requests (e.g., authentication flows) to bypass recording; use sparingly to avoid test flakiness.
- v4.0.7 is the latest release; migrations between major versions may require cassette regeneration.
When to avoid it — and what to weigh
- You need dynamic response validation — If tests require responses that change based on current timestamp, random values, or external state, replayed cassettes will not capture real-time variations.
- You're testing real-time or streaming APIs — go-vcr is designed for request/response pairs; streaming, WebSocket, or event-driven protocols are not well-suited to cassette replay.
- Your tests exercise multiple concurrent HTTP flows — Matching and replaying concurrent requests requires careful setup; simpler tools or genuine mocking may be cleaner for complex concurrency scenarios.
- You need to test API error recovery without fixed responses — If tests must validate behavior against varied error conditions (timeouts, 5xx, rate limits), cassettes lock responses and limit scenario coverage.
License & commercial use
BSD-2-Clause license is a permissive open-source license allowing commercial use, modification, and distribution with minimal restrictions (retain license and copyright notice).
BSD-2-Clause permits commercial use without explicit permission. Ensure your own code and cassette data do not contain third-party IP; cassettes themselves may contain captured API responses subject to those APIs' terms of service.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Active |
| Documentation | Strong |
| License clarity | Clear |
| Deployment complexity | Low |
| DEV.co fit | Good |
| Assessment confidence | High |
Cassette files in YAML format store full HTTP request/response bodies including headers and payload; design cassette storage to protect against unauthorized access. Use BeforeSaveHook to redact credentials, tokens, and PII before committing cassettes. No built-in encryption; if cassettes contain sensitive data, apply file-level or repository-level access controls.
Alternatives to consider
httptest + http.Client mocking
Go standard library alternative; fully deterministic but requires manual request/response setup per test; lower maintenance overhead for simple cases.
govcr (fork/alternative VCR library)
Alternative VCR implementation; feature and API design may differ; consider if go-vcr's v4 API does not fit your workflow.
mock/stub HTTP clients (testify/mock, etc.)
Fine-grained control via standard mocking frameworks; avoids cassette file management but requires explicit response setup for each test case.
Build on go-vcr with DEV.co software developers
Integrate go-vcr into your test suite to eliminate external API dependencies and ensure repeatable, fast test runs. Our team can help design a cassette management strategy for your project.
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go-vcr FAQ
What happens if I change my code but the cassette is stale?
Can I use go-vcr in production?
How do I prevent API credentials from being stored in cassettes?
Does go-vcr work with concurrent requests?
Software development & web development with DEV.co
DEV.co is a software development company delivering production systems to teams building on open source. Our engineers design, integrate, and ship across web, APIs, AI, data, and cloud. If go-vcr is part of your open-source testing roadmap, we can implement, customize, migrate, and maintain it.
Ready to accelerate your Go testing?
Integrate go-vcr into your test suite to eliminate external API dependencies and ensure repeatable, fast test runs. Our team can help design a cassette management strategy for your project.