100 API Development Apps for Building, Testing, and Managing APIs
API work spans far more than sending requests: teams also need tools for design, testing, documentation, gateways, mocks, and monitoring. This first installment covers 25 widely used options across those workflows.
Postman
Postman lets developers create, send, organize, test, and automate HTTP API requests within collaborative workspaces. It reduces scattered manual request testing by keeping collections, environments, scripts, and API documentation together.
Insomnia
Insomnia is an API client for designing requests, managing environments, testing endpoints, and working with specifications. It helps developers avoid repeatedly rebuilding complex requests when switching between local, staging, and production environments.
SwaggerHub
SwaggerHub provides collaborative hosting, editing, versioning, and governance tools for OpenAPI and AsyncAPI definitions. It addresses specification drift by giving teams a shared, versioned location for API contracts.
Stoplight
Stoplight helps teams design, document, review, and govern APIs using OpenAPI-based development workflows. It reduces ambiguity before implementation by enabling stakeholders to review API contracts and documentation early.
Hoppscotch
Hoppscotch is a web-based API client for sending HTTP, GraphQL, WebSocket, and Server-Sent Events requests. It helps developers quickly inspect endpoints without installing a heavyweight desktop application for basic request testing.
Bruno
Bruno is an offline-first API client that stores request collections directly as files in local folders. It solves collection version-control friction by allowing API requests to live alongside code in Git repositories.
Apidog
Apidog combines API design, documentation, debugging, mocking, and testing tools around shared API specifications. It helps teams reduce tool switching when moving from an API contract to implementation testing.
SoapUI
SoapUI supports functional and exploratory testing for SOAP and REST APIs through requests, assertions, and projects. It helps teams validate older SOAP services alongside REST endpoints without maintaining separate testing approaches.
Swagger Editor
Swagger Editor is a browser-based editor for writing and validating OpenAPI definitions with live documentation previews. It catches structural specification errors while authors write, preventing malformed API contracts from spreading downstream.
OpenAPI Generator
OpenAPI Generator creates client libraries, server stubs, documentation, and configuration artifacts from OpenAPI definitions. It reduces repetitive integration coding by generating language-specific scaffolding from a maintained API contract.
Redocly
Redocly provides tooling for validating, bundling, governing, and publishing OpenAPI documentation and reference portals. It helps teams keep public API references consistent by applying validation and documentation workflows to specifications.
RapidAPI Hub
RapidAPI Hub is a marketplace and developer platform for discovering, testing, and consuming published APIs. It shortens API discovery by letting developers explore available third-party endpoints from one catalog.
Kong Gateway
Kong Gateway is an API gateway that manages routing, authentication, traffic control, and plugin-based API policies. It centralizes cross-cutting API controls, reducing the need to implement authentication and rate limiting repeatedly.
Google Apigee
Google Apigee is an API management platform for proxies, security policies, analytics, developer portals, and lifecycle controls. It helps organizations expose APIs consistently when multiple backend services require shared access and governance rules.
Amazon API Gateway
Amazon API Gateway creates, publishes, secures, and monitors HTTP, REST, and WebSocket APIs on AWS. It reduces infrastructure management work for teams connecting client applications to AWS-based backend services.
Azure API Management
Azure API Management publishes APIs through gateways, applies policies, and offers developer portal capabilities. It helps Azure teams standardize API access controls without embedding identical policies in every backend.
MuleSoft Anypoint Platform
MuleSoft Anypoint Platform supports API design, integration development, deployment, management, and reusable asset sharing. It addresses fragmented enterprise integrations by connecting APIs, applications, and data sources through one platform.
Tyk
Tyk is an API management platform offering gateways, authentication, rate limiting, analytics, and developer portals. It helps teams apply consistent API policies across services rather than configuring protections independently.
Gravitee
Gravitee provides API management and access management products for securing, publishing, and monitoring digital APIs. It helps organizations manage API exposure when different consumers need different authentication and access policies.
WSO2 API Manager
WSO2 API Manager supports the full API lifecycle with publishing, gateways, security, analytics, and developer portals. It reduces lifecycle handoffs by bringing API publishing, consumption, and operational policy management into one system.
NGINX
NGINX serves as a web server, reverse proxy, load balancer, and API traffic management layer. It helps services handle incoming API traffic reliably by centralizing proxying, routing, and load balancing.
Mockoon
Mockoon is a desktop application for creating and running local mock APIs with configurable routes and responses. It lets frontend teams continue development when real backend endpoints are unfinished, unavailable, or unstable.
WireMock
WireMock simulates HTTP APIs through configurable stubs, request matching, response templating, and test integrations. It makes automated tests more predictable by replacing unreliable external dependencies with controlled API responses.
Prism
Prism validates API requests and responses against OpenAPI descriptions and can provide mock responses. It detects contract mismatches early by checking implementation traffic against the documented OpenAPI specification.
Dredd
Dredd tests whether an API implementation conforms to the HTTP API description written in an API blueprint. It helps prevent documentation drift by automatically comparing running API behavior with its declared contract.
FastAPI
FastAPI is a Python framework for building typed HTTP APIs with automatic OpenAPI documentation. It reduces manual validation and documentation work when Python services expose many structured endpoints.
Express
Express is a Node.js web framework for creating HTTP routes, middleware, and API services. It helps teams organize server-side request handling without building routing infrastructure from scratch.
NestJS
NestJS is a Node.js framework for building modular server applications using TypeScript and decorators. It gives growing APIs a consistent architecture when loosely organized Node.js code becomes difficult to maintain.
Django REST Framework
Django REST Framework provides serializers, authentication, permissions, and view tools for Django APIs. It streamlines exposing Django models through APIs while enforcing common access-control and validation patterns.
Flask
Flask is a lightweight Python framework for creating web applications and RESTful API endpoints. It helps developers launch small Python services without adopting a large, opinionated application framework.
Hono
Hono is a lightweight web framework designed for JavaScript runtimes including edge environments. It simplifies building portable HTTP APIs across edge and serverless runtime deployments.
Koa
Koa is a Node.js web framework that uses middleware to compose HTTP application behavior. It helps developers manage asynchronous request processing with a smaller foundation than full-featured frameworks.
Fastify
Fastify is a Node.js web framework for building APIs with schema-based validation and serialization. It reduces repetitive input-checking code for teams maintaining many structured API routes.
Spring Boot
Spring Boot helps Java developers create standalone web services and production-ready API applications. It simplifies Java service setup by providing conventions for configuration, dependencies, and web endpoints.
ASP.NET Core
ASP.NET Core is Microsoft's cross-platform framework for building web applications and HTTP APIs. It helps.NET teams create modern APIs that run across supported operating systems and cloud environments.
Laravel
Laravel is a PHP framework offering routing, database tools, authentication, and API development features. It reduces boilerplate when PHP teams need database-backed endpoints with common application capabilities.
Ruby on Rails
Ruby on Rails is a web framework that supports database-backed applications and JSON API responses. It helps small teams move from data models to working application endpoints with fewer conventions to invent.
Gin
Gin is a Go web framework for building HTTP services with routing and middleware. It provides Go developers a focused structure for creating API handlers without assembling basic web components.
Fiber
Fiber is a Go web framework for creating web applications and HTTP API services. It helps Go teams implement route handling and middleware quickly for lightweight backend services.
Actix Web
Actix Web is a Rust framework for building asynchronous web applications and API servers. It gives Rust developers structured tools for handling concurrent HTTP requests in backend services.
tRPC
tRPC enables TypeScript applications to call backend procedures with end-to-end type inference. It reduces duplicated client and server type definitions in TypeScript applications with internal APIs.
Apollo Server
Apollo Server is a GraphQL server for defining schemas and resolving client data requests. It helps teams consolidate multiple client data requirements behind a typed GraphQL API layer.
Hasura
Hasura creates GraphQL APIs over connected databases and supports authorization rules and actions. It accelerates data API creation when teams need GraphQL access without hand-writing every resolver.
GraphQL Yoga
GraphQL Yoga is a GraphQL server library for building schema-based APIs across JavaScript environments. It helps developers add GraphQL endpoints without coupling their server implementation to one framework.
PostgREST
PostgREST automatically provides a RESTful API directly from a PostgreSQL database schema. It avoids writing routine CRUD endpoints when PostgreSQL tables already define the underlying data model.
Supabase
Supabase provides backend services including a PostgreSQL database and automatically generated data APIs. It helps teams start database-backed applications without separately configuring foundational backend services.
Strapi
Strapi is a headless CMS for creating content types and exposing them through APIs. It gives teams a managed interface for editorial data instead of hand-building content administration endpoints.
Directus
Directus provides a data platform that exposes connected databases through REST and GraphQL APIs. It helps teams give nontechnical colleagues controlled data access without developing a custom administration layer.
LoopBack
LoopBack is a Node.js framework for building APIs around data sources and application models. It reduces integration effort when an API must connect consistently to multiple databases or services.
FeathersJS
FeathersJS is a Node.js framework for creating REST APIs and real-time application services. It helps developers support both HTTP and real-time interactions without maintaining separate backend stacks.
AdonisJS
AdonisJS is a Node.js framework providing routing, validation, authentication, and database tools for APIs. It helps teams avoid assembling common backend components separately when starting a structured API project.
Sails.js
Sails.js is a Node.js framework that builds data-driven APIs with conventions and WebSocket support. It helps developers create CRUD-oriented endpoints faster without hand-writing repetitive controller and model scaffolding.
Micronaut
Micronaut is a JVM framework for building modular services and APIs with compile-time dependency injection. It helps reduce startup and memory overhead that can complicate deployment of Java-based API services.
Quarkus
Quarkus is a Java framework for building cloud-native APIs and services with developer-focused tooling. It helps Java teams package services for containers while retaining familiar enterprise Java programming models.
Ktor
Ktor is a Kotlin framework for creating asynchronous servers, REST APIs, and client applications. It helps Kotlin developers build lightweight HTTP services without adopting a larger Java framework stack.
Phoenix
Phoenix is an Elixir web framework for building fault-tolerant APIs and real-time applications. It helps teams manage many concurrent connections using Elixir's process-based concurrency model.
Play Framework
Play Framework is a web framework for Java and Scala applications with asynchronous HTTP handling. It helps JVM teams build non-blocking web APIs without configuring low-level server infrastructure manually.
Symfony
Symfony is a PHP framework and component ecosystem for building web applications and HTTP APIs. It helps PHP teams standardize routing, dependency management, validation, and request handling across API projects.
CodeIgniter
CodeIgniter is a lightweight PHP framework that provides routing, controllers, and database access for applications. It helps developers launch simple PHP APIs with less configuration than larger full-stack frameworks require.
CakePHP
CakePHP is a PHP framework offering convention-based development, ORM features, and RESTful application support. It helps teams reduce repetitive database and controller code through established project conventions.
Slim
Slim is a PHP microframework for creating HTTP APIs with routing, middleware, and request handling. It helps developers build focused PHP endpoints without adopting features unnecessary for small services.
Vapor
Vapor is a server-side Swift framework for building APIs, web services, and backend applications. It helps Swift developers use their existing language skills for backend API development.
Go kit
Go kit is a toolkit for building reliable Go microservices with transport and service abstractions. It helps Go teams apply consistent patterns for logging, metrics, transport, and service boundaries.
Echo
Echo is a Go web framework for building HTTP APIs with routing, middleware, and data binding. It helps Go developers implement API handlers quickly while keeping request processing explicit.
Chi
Chi is a lightweight Go router for composing RESTful HTTP services with standard library compatibility. It helps developers add flexible routing and middleware without replacing Go's native HTTP foundations.
Axum
Axum is a Rust web framework for building asynchronous HTTP APIs using the Tokio ecosystem. It helps Rust teams create typed request handlers while integrating with established asynchronous Rust libraries.
Rocket
Rocket is a Rust web framework that uses type-safe routing, request guards, and response handling. It helps developers catch many API input and routing mistakes during compilation rather than runtime.
Warp
Warp is a Rust web framework for composing HTTP APIs from filters and asynchronous handlers. It helps Rust developers build reusable request-processing pipelines for complex endpoint requirements.
Sanic
Sanic is an asynchronous Python web framework designed for fast HTTP servers and API applications. It helps Python teams handle asynchronous API workloads without adapting a synchronous framework architecture.
Falcon
Falcon is a minimalist Python framework for building high-performance RESTful APIs and microservices. It helps developers minimize framework overhead when creating straightforward resource-oriented Python APIs.
Litestar
Litestar is a Python framework for building APIs with type hints, dependency injection, and validation. It helps teams organize typed Python API services with reusable dependencies and automatic data handling.
Pyramid
Pyramid is a flexible Python web framework supporting URL dispatch, views, and extensible configuration. It helps developers scale an API architecture gradually without committing to rigid application conventions.
Bottle
Bottle is a single-file Python web framework for small web applications and HTTP APIs. It helps developers prototype compact API services with minimal dependencies and setup work.
Tornado
Tornado is a Python web framework and networking library for asynchronous web applications. It helps teams support long-lived connections and non-blocking requests in Python services.
aiohttp
aiohttp is an asynchronous Python library for building HTTP clients, servers, and WebSocket applications. It helps developers use one asyncio-based toolkit for both API consumption and server implementation.
REST Assured
REST Assured provides a Java DSL for automating HTTP API tests and validating responses. It helps Java teams replace repetitive request code with readable tests that catch response regressions.
Karate
Karate combines API testing, mocking, and performance testing using a human-readable domain-specific language. It helps teams test services without building extensive custom test frameworks or complex assertion code.
Pact
Pact supports consumer-driven contract testing between API consumers and service providers. It helps prevent integration breakages by verifying providers still meet consumers' agreed API expectations.
Schemathesis
Schemathesis generates property-based API tests from OpenAPI and GraphQL schemas. It helps developers uncover edge-case failures that manually written endpoint tests often miss.
k6
k6 lets developers script and run load tests for APIs and backend services. It helps teams identify performance bottlenecks before traffic spikes expose capacity or latency problems.
Apache JMeter
Apache JMeter creates and runs performance tests for web applications, APIs, and protocols. It helps teams simulate concurrent requests when assessing whether services can handle expected demand.
Gatling
Gatling is a load-testing platform that uses code-based simulations and detailed performance reports. It helps engineering teams automate repeatable performance checks within their continuous delivery workflows.
Artillery
Artillery provides scriptable load and functional testing for HTTP, WebSocket, and GraphQL services. It helps developers test real-time and API traffic patterns without constructing bespoke load generators.
Locust
Locust is an open-source load-testing tool that defines user behavior with Python code. It helps Python-oriented teams model realistic user traffic using familiar programming constructs.
HTTPie
HTTPie is a command-line and desktop client for sending HTTP requests and inspecting responses. It helps developers quickly explore endpoints with more readable commands and output than basic terminal tools.
curl
curl is a command-line tool for transferring data to and from servers using HTTP and other protocols. It helps developers reproduce requests directly in scripts, terminals, and automated troubleshooting workflows.
Fiddler Classic
Fiddler Classic captures, inspects, and modifies HTTP and HTTPS traffic between clients and servers. It helps developers diagnose unexpected requests or responses by exposing traffic flowing through their machine.
Charles Proxy
Charles Proxy records and inspects HTTP and HTTPS traffic from desktop and mobile applications. It helps teams debug mobile API calls when device-side behavior differs from local development expectations.
mitmproxy
mitmproxy is an interactive intercepting proxy for viewing, modifying, and replaying HTTP traffic. It helps developers investigate difficult network interactions by altering requests and responses during debugging.
Burp Suite
Burp Suite provides web security testing tools for examining APIs, requests, authentication, and vulnerabilities. It helps security-minded teams find weaknesses in exposed endpoints before attackers can exploit them.
OWASP ZAP
OWASP ZAP is an open-source security scanner and proxy for testing web applications and APIs. It helps smaller teams incorporate baseline security checks without building their own scanning tooling.
Sentry
Sentry monitors application errors and traces requests to help teams diagnose production failures. It helps developers connect API exceptions to affected requests, releases, and application code more quickly.
Datadog
Datadog collects metrics, logs, and traces for monitoring APIs, infrastructure, and application performance. It helps teams investigate distributed API incidents by correlating service health signals in one platform.
New Relic
New Relic provides observability tools for tracking application performance, errors, logs, and distributed traces. It helps developers locate slow API transactions across services instead of manually comparing separate monitoring sources.
Swagger UI
Swagger UI renders interactive documentation from OpenAPI definitions and lets users send sample requests. It helps API consumers understand available operations without deciphering raw specification files or handwritten documentation.
AsyncAPI
AsyncAPI provides a specification and tooling ecosystem for documenting event-driven APIs and message channels. It helps teams clarify asynchronous message contracts that are difficult to communicate through REST-focused documentation.
Bump.sh
Bump.sh publishes API documentation from OpenAPI and AsyncAPI definitions and tracks specification changes. It helps teams share evolving API contracts while making breaking or notable changes easier to review.
Speakeasy
Speakeasy generates SDKs, documentation, and developer experiences from OpenAPI specifications. It helps API providers reduce the work of maintaining client libraries across multiple programming languages.
Fern
Fern generates SDKs and API documentation from API definitions for developer-facing products. It helps teams deliver consistent client libraries without manually duplicating endpoint logic and types.
Scalar
Scalar provides tools for rendering OpenAPI documentation and testing API requests through interactive interfaces. It helps developers offer clearer API reference material without building a custom documentation frontend.
The right stack depends on where your API workflow has the most friction, from early contract design to production traffic management.