Optic

Open-source API governance tool for detecting breaking changes in OpenAPI specs

API Development www.useoptic.com

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About Optic

<p>Optic is an open-source API governance platform that helps development teams prevent breaking changes, enforce API design standards, and keep OpenAPI documentation accurate. Built on a high-performance Rust engine, Optic diffs API specifications to detect breaking and non-breaking changes, runs configurable linting rules, and integrates directly into CI/CD pipelines and pull request workflows.</p><p>Originally a Y Combinator-backed startup, Optic was acquired by Atlassian in April 2024 and integrated into Compass, Atlassian's developer experience platform. The open-source CLI remains freely available on GitHub and npm, processing everything locally without sending API data to external servers. Optic's "forwards-only governance" approach applies new rules only to new or changed endpoints, making it practical to adopt incrementally without retroactively breaking existing APIs.</p>

Pros & Cons

Pros

Completely free and open-source CLI with no usage limits
Detects breaking changes that standard linters miss by diffing spec versions
Forwards-only governance avoids flooding teams with legacy warnings
Local Rust-based processing keeps API schemas private and runs fast
Precision-patches OpenAPI specs from test traffic, reducing manual spec writing
Strong CI/CD integration for automated API review in pull requests
Backed by Atlassian with active development and Compass integration

Cons

Cannot generate OpenAPI specs from scratch — requires an existing specification to work with
HTTPS traffic capture can be complex to configure due to encryption proxying requirements
Cloud/team features now tied to Atlassian Compass ecosystem after acquisition
Smaller community compared to established API tools like Swagger or Postman
Documentation can be sparse for advanced configuration and custom rule authoring

Key Features

OpenAPI Diffing

Compares two versions of an OpenAPI specification to detect all breaking and non-breaking changes, giving developers a clear changelog of what shifted between releases

Breaking Change Detection

Automatically identifies changes that could break API consumers — removed endpoints, changed response schemas, modified required parameters — before they reach production

API Linting & Style Guides

Enforces API design standards and best practices through configurable linting rules and custom style guides that run alongside diff checks

CI/CD & PR Integration

Runs in pull requests to give developers actionable feedback on API changes before merge, with support for GitHub Actions and other CI platforms

Forwards-Only Governance

Applies new linting rules only to new or changed API endpoints, avoiding false positives on legacy APIs and making incremental adoption practical

Traffic-Based Documentation

Captures API traffic from tests, compares it against the OpenAPI spec, and precision-patches the specification with additions, updates, and removals automatically

Local Processing

All specification analysis runs locally via a compiled Rust binary — no API data is sent to external servers, keeping sensitive schemas private

Multi-Spec Repository Support

Discovers and tracks all OpenAPI specifications in a repository, running governance checks across the entire API surface from a single configuration

Pricing

Open Source CLI

$0/month

OpenAPI diffing and breaking change detection
API linting and custom style guides
CI/CD pipeline integration
Traffic-based spec patching
Local processing (Rust engine)
GitHub Actions support
Community support via GitHub

Atlassian Compass

Contact Sales

Everything in Open Source CLI
API documentation publishing to Compass
Team-wide API change notifications
API analytics and history
Centralized API catalog
Atlassian ecosystem integration

Best For

API Versioning & Release Management

Teams shipping public or partner-facing APIs use Optic in CI to catch breaking changes before they reach production, preventing downstream consumer breakage during releases.

API Design Governance

Platform engineering teams enforce consistent API design standards across microservices by running Optic's linting rules in every pull request, ensuring naming conventions and patterns stay uniform.

OpenAPI Documentation Accuracy

Development teams use Optic's traffic capture to automatically keep OpenAPI specs in sync with actual API behavior, eliminating drift between documentation and implementation.

CI/CD API Quality Gates

Engineering organizations add Optic as a quality gate in their CI pipelines to block merges that introduce breaking changes or violate API style guides without manual review.