# microsoft/restler-fuzzer

RESTler is the first stateful REST API fuzzing tool for automatically testing cloud services through their REST APIs and finding security and reliability bugs in these services.

Repository: https://github.com/microsoft/restler-fuzzer
Canonical: https://ross.abutalabs.com/products/restler-fuzzer
Language: Python
License: MIT
License Family: permissive
Last push: 2026-06-10T13:05:25+00:00

## Health v2 (maintenance only)
Score: 71/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 86, release rhythm 35, longevity 100
- inputs: {"age_days": 2231, "days_push": 84, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2939, forks 331 (observed 2026-08-28T04:07:30.972639+00:00)

## What it is
RESTler is the first stateful REST API fuzzing tool, automatically testing cloud services through their REST APIs to find security and reliability bugs. It infers producer-consumer dependencies from OpenAPI specifications and generates request sequences that explore deeper service states.

## Use cases
- fuzz a rest api for security bugs
- automatically test cloud service endpoints from an openapi spec
- find crashes and reliability bugs in rest apis
- generate stateful api request sequences for testing
- regression testing for rest apis
- check security properties of api endpoints

## When to choose
- you have an OpenAPI/Swagger specification for a REST API you want to test
- you need automated discovery of security and reliability bugs in cloud services
- you want stateful fuzzing that explores multi-request sequences
- you need a research-backed fuzzing tool with multiple test generation strategies

## When to avoid
- your service has no OpenAPI specification available
- you need to test GraphQL, gRPC, or non-REST interfaces
- you want simple load or performance testing rather than bug finding
- you need a GUI-driven manual API testing tool like Postman

## Facets
- artifact type: cli-tool
- maturity: active
- function: fuzzing, testing, security, vulnerability-scanning, http-client
- domain: security, testing, apis, developer-tools
- platform: windows, python, cli
- tags: rest-api, openapi, stateful-fuzzing, api-testing, microsoft-research, linux, macos, docker

## Member repositories
- microsoft/restler-fuzzer (main) score 71

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:30.972639+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 2026-08-30T07:32:58.319604+00:00, confidence not recorded.
  - readme: https://github.com/microsoft/restler-fuzzer (fetched 2026-08-28T04:07:30.972639+00:00, sha 9ca0ad6a6bf7)
- Data as of 2026-08-30T08:39:29.467469+00:00.