Code linting and validation are core components of good code development in 2025. Below, we’ll look at a spate of options in this space, identifying some top contenders for different languages, frameworks, and approaches.

A Quick Overview: What is Linting and Validation?

Before we dig into the specific items on this list, we should briefly define what API linting and validation even are.

API linting is the process of enforcing consistency within a codebase through the analysis of API specifications against a predefined set of rules and best practices. Linting helps catch issues before the API is deployed and can help ensure compliance with standard design methodologies such as RESTful design or HTTP verbiage usage.

A simple example of linting would be checking the use of camelCase vs. snake_case. While there is no universal standard (save for specific instance guidelines such as Google’s JSON guide), a linter can help you ensure that your choice is actually consistent. If most of your codebase uses camelCase except for a small subsection, a linter can help identify this against a specification file and ensure that you are applying the same standard universally.

API validation is the process of checking that an API functions as intended, focusing on request and response formats, data consistency, and schema compliance. Validators are less concerned with stylistic choices and more focused on whether the API behaves according to its specification.

10 API Linters and Description Validators

With this in mind, let’s look at some great API linters and description validators. These solutions all have their merits, but their utility will vary depending on your use case, language of choice, and design environment. Consider this a list of solid options — do your due diligence when testing them out.

1. LintGPT

LintGPT is a great example of a new class of tools: AI-enriched linting. These kinds of tools utilize AI rather than just a 1:1 comparison approach to ensure that bugs, stylistic issues, and other common mistakes are identified and fixed. Notably, Optic’s implementation supports capture snapshots for OpenAPI testing, allowing you to use real traffic to validate linting in practice.

Benefits

• AI-augmented: By leveraging AI, LintGPT opens up a world of efficiency for use cases that benefit from intelligent linting against specific rules and configurations.
• Error clarity: This tool uses plain language to explain errors, offering clarity that other tools often lack.

2. Spectral

Spectral is an open-source linter with support for JSON and YAML. It offers extensions for various platforms and solutions, allowing you to integrate it into almost any workflow. Spectral offers extensive customization options, supporting custom rules, JSONPath and JSONPathPlus testing integration, and more.

Benefits

• Highly customizable: Spectral supports YAML/JSON rulesets for OpenAPI, Arazzo, and AsyncAPI linting and validation.
• Extensible: Can be built into virtually any IDE or CI/CD pipeline.

3. Redocly CLI

Redocly CLI is a command-line tool for linting and validating OpenAPI or Arazzo specifications. With its lint command, you can check API definitions against built-in or custom rulesets. The tool also supports various output formats for easy integration into your workflow.

Benefits

• Developer experience: Sits right in your terminal for easy, simple commands.
• Flexibility: Supports custom rulesets and multiple output styles.

4. Vacuum

Vacuum is an OpenAPI linter designed for speed and efficiency. Written in Go, it’s best suited for high-performance environments with large-scale systems. Vacuum generates Spectral-compatible reports, allowing for easy integration into Spectral-based workflows.

Benefits

• Fast and lightweight: Built for speed and low overhead.
• Low dependencies: Requires minimal dependencies, increasing processing efficiency.

5. Zally

Zally is an OpenAPI linter that provides both a CLI tool and a linting server. Built by Zalando, it is a great choice for enforcing governance in multi-service or multi-API environments. It uses Zalando’s own RESTful guidelines by default but supports custom rules.

Benefits

• Enterprise-grade: Designed for large-scale API governance.
• Supports server and CLI modes: Run locally or as a service.

6. IBM OpenAPI Validator

The IBM OpenAPI Validator is part of IBM’s API Connect toolkit. While tightly integrated into the IBM ecosystem, it can also be used as a standalone solution. It’s designed to align API development with best practices.

Benefits

• Opinionated with IBM: Enforces IBM’s best practices for API design.
• Linting and validation combined: Offers a comprehensive set of checks in one tool.

7. OpenAPI Spec Validator

The OpenAPI Spec Validator is a minimal and straightforward tool for validating OpenAPI specifications across v2 and v3. It’s easy to integrate as a Python hook or package, though its utility is more limited outside Python environments.

Benefits

• Minimalistic: Simple to use and deploy.
• Useful for testing pipelines: Excellent as a validation hook in CI/CD setups using Python.

8. ESLint

ESLint is a general-purpose linter widely used in JavaScript, TypeScript, and React projects. Its deep integration with popular IDEs and editors makes it easy to plug into your workflow.

Benefits

• Wide adoption: Strong community support and ecosystem integration.
• Identifies code smells: Surfaces potential issues that might affect long-term code health.

9. Pylint

Pylint is a Python-specific linter widely used in API development with frameworks like Flask and FastAPI. It offers static code analysis and suggests refactoring but does not automatically fix issues by default.

Benefits

• Opinionated but flexible: Offers recommendations without forcing changes.
• PEP 8 compliant: Aligns with Python’s official code style guide.

10. GolangCI-Lint

GolangCI-Lint is a linter built specifically for Go projects. Go’s popularity in high-performance APIs makes this tool especially valuable. It supports parallel processing and integrates with major IDEs.

Benefits

• Parallel processing: Improves speed and efficiency during linting.
• Efficient: Optimized for large-scale codebases.

Additional OpenAPI Scanners

Plenty of other tools can help assess the quality and security of your OpenAPI files. Free tools like RateMyOpenAPI or APIInsights, for instance, provide overall quality scores that align with industry best practices. There are also more security-focused vulnerability scanners, like OpenAPI.security and Apisec.

Tools for API Linting and Validating

Linters and validators play a huge and crucial role in API design and governance. These tools help streamline development processes, enforce standards, and produce more robust, maintainable code. While they vary in language focus, error detection approach, and feature set, they all serve the common purpose of helping you build better APIs. Do your due diligence and pick a tool to try out today!