# SpectoLabs/hoverfly

Lightweight service virtualization/ API simulation / API mocking tool for developers and testers

Repository: https://github.com/SpectoLabs/hoverfly
Canonical: https://ross.abutalabs.com/products/hoverfly
Homepage: https://hoverfly.io
Language: Go
License: Apache-2.0
License Family: permissive
Topics: api-simulation, golang, proxy, mitm, testing-tools, mocking, stubbing, service-virtualization, http, https, testing, go, hoverfly, api-mock, api-mocking, rest-api
Last push: 2026-08-24T00:59:05+00:00

## Health v2 (maintenance only)
Score: 99/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 99, longevity 100
- inputs: {"age_days": 3929, "days_push": 10, "days_rel": 10, "gap_med": 17.5, "n_releases_24m": 27}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2509, forks 228 (observed 2026-08-28T04:06:57.296885+00:00)

## What it is
Hoverfly is a lightweight open-source API simulation and service virtualization tool written in Go. It captures HTTP/HTTPS traffic and replays it as simulations, allowing developers and testers to replace real API dependencies with fast, controllable mocks.

## Use cases
- mock external APIs during integration testing
- simulate slow or flaky third-party API dependencies
- simulate network latency, random failures, and rate limits
- capture real HTTP traffic and replay it as stubs
- run API mocks in CI pipelines instead of live sandboxes
- virtualize REST APIs that are not yet built

## When to choose
- you need HTTP/HTTPS API mocking or service virtualization in tests
- your test suites are slowed by unavailable or unreliable downstream APIs
- you want to test edge cases like latency, failures, and rate limiting
- you prefer a lightweight, self-hosted alternative to commercial virtualization tools

## When to avoid
- you need to virtualize non-HTTP protocols like databases or message queues
- you want a hosted, managed simulation platform (consider Hoverfly Cloud)
- you only need simple unit-test mocks in a single language where a library-level mock suffices

## Facets
- artifact type: cli-tool
- maturity: active
- function: testing, mocking, http-server, proxy, middleware
- domain: testing, developer-tools, apis, web-development
- platform: cross-platform, cli, go
- tags: api-simulation, service-virtualization, api-mocking, stubbing, mitm-proxy, http-mocking, test-doubles, automation, docker

## Member repositories
- SpectoLabs/hoverfly (main) score 99

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:57.296885+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:26:26.930367+00:00, confidence not recorded.
  - readme: https://github.com/SpectoLabs/hoverfly (fetched 2026-08-28T04:06:57.296885+00:00, sha a4ba8ff10b3c)
  - homepage: https://hoverfly.io (fetched 2026-08-29T10:08:50.529904+00:00, sha 8b30c233b809)
  - site_page: https://docs.cloud.hoverfly.io/ (fetched 2026-08-29T10:08:50.534387+00:00, sha 20b005c511d3)
  - site_page: https://hoverfly.io/pricing (fetched 2026-08-29T10:08:50.532642+00:00, sha adec026e92be)
  - site_page: https://hoverfly.io/blog/tag/releases (fetched 2026-08-29T10:08:50.536098+00:00, sha 22a5c458c9b0)
- Data as of 2026-08-30T08:39:29.467469+00:00.