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Zally

opensource.zalando.com

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Spec score 7.8 #15 of 25 in API Governance Software

What it is

Zally is an API linter and quality assurance tool for OpenAPI specifications. It supports OpenAPI 3 and Swagger OpenAPI 2, with a RESTful API, command-line interface, and web interface. Its standard configuration checks APIs against Zalando’s RESTful Guidelines, and the project says it can also be used out of the box by others. Teams can enable or disable server-side rules, configure some existing rules, or implement their own in Kotlin. An API definition can use the x-zally-ignore extension to disable rules for that API. The web interface lists implemented rules and can lint external files and API definitions in its online editor. The project describes starting the web UI, server, and database together using Docker Compose. It also lists an unofficial Zally Maven Plugin integration. Maintained by Zalando, Zally is offered under an MIT license with an exception. Its Open source plan costs nothing.

Spec sheet

Purpose
Zally is an API linter and quality assurance tool for OpenAPI specifications.Read 8 Oct 2026 · github.com
Platforms
The release page lists Zally CLI downloads for Linux, macOS, and Windows.Read 8 Oct 2026 · github.com
Integrations
The README lists an unofficial Zally Maven Plugin integration.Read 8 Oct 2026 · github.com
Security
The repository has a security policy page, but the opened policy page did not expose its policy text.Read 8 Oct 2026 · github.com
Support
The project invites users to join its Gitter room or contact maintainers directly.Read 8 Oct 2026 · github.com
License
The project is offered under an MIT license with an exception.Read 8 Oct 2026 · github.com
Maker
The project says it is maintained by Zalando.Read 8 Oct 2026 · opensource.zalando.com
Customization
Users can enable or disable server-side rules, configure some existing rules, and implement custom rules in Kotlin.Read 8 Oct 2026 · opensource.zalando.com
Guidelines
Its standard configuration checks APIs against Zalando’s RESTful Guidelines, and the project says it can also be used out of the box by others.Read 8 Oct 2026 · opensource.zalando.com
Integration
The README lists a Zally Maven Plugin integration and labels it unofficial.Read 8 Oct 2026 · github.com
Interfaces
Zally provides a RESTful API, a CLI, and a web interface.Read 8 Oct 2026 · github.com
Local deployment
The project README says the web UI, server, and database can be started together with Docker Compose.Read 8 Oct 2026 · github.com
Maintainer
The project site says Zally is maintained by Zalando.Read 8 Oct 2026 · opensource.zalando.com
OpenAPI support
It supports OpenAPI 3 and Swagger OpenAPI 2 specifications.Read 8 Oct 2026 · github.com
Rule exceptions
The x-zally-ignore extension lets users disable rules for a specific API.Read 8 Oct 2026 · github.com
Security reporting
The repository security policy says vulnerability reports can be submitted through Zalando’s form and that its HackerOne bug bounty program is private.Read 8 Oct 2026 · github.com
Self-hosting
The README describes running the web UI, server, and database together with Docker Compose.Read 8 Oct 2026 · github.com
Specification support
It supports OpenAPI 3 and Swagger OpenAPI 2 specifications.Read 8 Oct 2026 · github.com
Web UI
The web UI lists implemented rules and can lint external files and API definitions in its online editor.Read 8 Oct 2026 · opensource.zalando.com

Plans and prices

Open source Free MIT license with an exception · API linter Read 8 Oct 2026 · github.com

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Strong points and limits

Strong points

  • Supports OpenAPI 2 and OpenAPI 3
  • Provides REST API, CLI, and web interface
  • Custom rules can be implemented in Kotlin
  • Free under an MIT license with an exception

Limits

  • Access control level is basic
  • Maven Plugin integration is unofficial

Who it suits

It suits teams that want to lint OpenAPI 2 or 3 specifications against Zalando’s guidelines or customized rules. The CLI, REST API, web interface, and Docker Compose setup give teams several ways to use it.

Verdict

Zally focuses on API style checks, with adjustable rules and support for custom Kotlin rules. It is free and open source, though its listed access control is basic.

Where Specifiction places it

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