REST Lens

REST Lens - Enterprise API Quality Assurance

Evaluate OpenAPI Specifications with Confidence

REST Lens provides comprehensive static analysis of RESTful API specifications, helping you build better APIs through automated quality checks and best practice enforcement. Delivered as a premium SaaS solution by E.SU. IT AB.

What is REST Lens?

REST Lens is a powerful tool developed for API designers, developers, and architects who want to ensure their REST APIs adhere to best practices and design standards. Developed by E.SU. IT AB based on academic research, this solution provides enterprise-grade API quality assurance as a Software-as-a-Service (SaaS) platform.

Key Features

Comprehensive Analysis

Upload your OpenAPI specifications and receive detailed feedback on potential design issues, inconsistencies, and violations of REST best practices.

Semantic Analysis

Unlike traditional linters that rely on regex and JSONPath pattern matching, REST Lens uses semantic analysis to understand the meaning of your API, not just syntax patterns:

  • Plural detection: Knows "users" is a collection while "status" is a legitimate singleton endpoint
  • Tunneling detection: Reads operation summaries to catch anti-patterns like "Delete user via POST" that violate REST principles
  • Hierarchy validation: Understands when query parameters should be path parameters based on resource relationships (e.g., user_id should be in the path /users/{id}/posts, not a query param)
  • Domain awareness: Adapts to domain-specific terminology without requiring complex regex configuration

Result: Fewer false positives, catches issues regex can't see, and adapts intelligently to your API's unique structure and naming conventions.

Smart Caching for Fair Pricing

Every semantic analysis is cached intelligently in a multi-tier system to ensure you only pay for actual work:

  • Linguistic facts (e.g., "is 'users' plural?"): cached for 180 days
  • Context-dependent checks: cached for 14 days
  • Spec + rule hash matching: instant results for unchanged specifications

When you re-evaluate the same specification, the second evaluation is nearly free thanks to cache hits. You pay only for genuine analysis work, not repeated computations.

Interactive Visualization

Explore your API's structure and identified issues through an intuitive, interactive web interface with support for both light and dark modes.

Customizable Rule System

Configure which rules to apply and their specific parameters to match your organization's API design standards and preferences.

Custom Rules

Define your own organization-specific rules using a simple YAML syntax. Import existing Spectral rulesets or create rules from scratch to enforce your unique API design standards across all projects.

Versioning Support

Compare multiple versions of your API specifications to track improvements and ensure consistent design across revisions.

Use Cases

For API Designers

  • Validate design decisions against REST best practices
  • Ensure consistent naming conventions and resource structures
  • Identify potential usability issues before implementation

For Development Teams

  • Enforce team-wide API design standards
  • Catch design issues early in the development lifecycle
  • Improve API quality and consistency across projects

For Organizations

  • Standardize API design across multiple teams and services
  • Reduce friction in API integration and consumption
  • Build more maintainable and future-proof API ecosystems

How It Works

  1. Upload your OpenAPI specification (JSON or YAML format)
  2. Analyze your API against dozens of REST design rules
  3. Review detailed findings organized by severity and category
  4. Configure rules to match your specific requirements
  5. Export findings for documentation or team review

Technical Features

  • Modern Stack: Python/FastAPI backend, React/TypeScript frontend
  • Docker Support: Easy deployment with containerization
  • Extensibility: Create custom rules using YAML syntax or import from existing Spectral rulesets
  • Performance: Fast analysis even for large API specifications
  • Visualization: Tree-based representation of API paths and structures

Getting Started

Access REST Lens SaaS

REST Lens is available exclusively as a Software-as-a-Service (SaaS) offering. No installation or configuration is required.

  1. Visit https://restlens.com to create an account
  2. Choose a subscription plan that matches your needs
  3. Upload your OpenAPI specifications and start analyzing

Enterprise customers can contact our sales team for custom pricing and dedicated support options.

Research-Based Expertise

REST Lens is built on a foundation of academic research in RESTful API design principles, focusing on static analysis of OpenAPI specifications. Originally developed as part of academic study on REST API best practices, the technology has been enhanced with industry experience and expertise. Our team continuously refines and enhances our ruleset to ensure it reflects the latest standards and practices in API design.

REST Best Practices Evaluated

  • Resource Naming: Consistent pluralization, casing, and URL structures
  • HTTP Method Usage: Appropriate verb selection for different operations
  • Status Codes: Proper use of status codes and response structures
  • Error Handling: Consistent error formats and appropriate status codes
  • Pagination: Implementation of standard pagination patterns
  • Filtering: Query parameter design and implementation
  • Hierarchical Resources: Proper representation of resource relationships
  • Content Negotiation: Support for multiple representation formats
  • And many more...

Enterprise-Ready Solution

REST Lens is designed to meet the needs of organizations of all sizes. Our SaaS platform provides a scalable solution with enterprise-grade security, reliability, and performance. Contact our sales team to discuss how REST Lens can be tailored to your specific requirements.