Backed by nearly 80,000 GitHub stars and recognized as one of the most popular developer tools in the open-source ecosystem, Hoppscotch delivers a complete API development platform that runs instantly in any browser with zero installation. The platform supports six protocols out of the box including REST with full HTTP method coverage, GraphQL with schema introspection and multi-column documentation, WebSocket for full-duplex communication, Socket.IO, MQTT for IoT messaging, and Server-Sent Events for real-time streaming. Request collections organize your API calls into logical groups with support for sub-folders, environment variables with scope inheritance, pre-request scripts and post-request test scripts written in JavaScript, and automatic code snippet generation in over twenty languages and frameworks. Teams can collaborate in real-time with shared workspaces, role-based access controls, and cloud synchronization across devices. Migration from Postman, Insomnia, or OpenAPI specifications happens with a single click import. The self-hosted edition deploys via Docker Compose with PostgreSQL for data persistence, supporting SSO authentication through SAML and OAuth providers, SMTP configuration with OAuth2, and admin dashboard for user management. The platform also ships as a native desktop application for macOS, Windows, and Linux with offline support, plus a CLI tool for running collections in CI/CD pipelines. A built-in proxy mode bypasses CORS restrictions during development, and an interceptor enables request debugging and response modification. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Yet Another API Development Environment delivers a self-hosted alternative to Postman designed from the ground up for teams that need secure, collaborative API development without sending sensitive credentials through third-party cloud services. The multi-user system manages team members with role-based permissions and supports external authentication through OAuth2 and OIDC providers, while all data persists in an H2 file-based database that survives container and server restarts. REST and WebSocket request testing includes environment variable substitution, request chaining, and Markdown documentation for each endpoint. The JavaScript scripting engine runs request and response scripts for automated testing and data extraction, with cron job scheduling and API-triggered execution for continuous integration workflows. Collections import directly from OpenAPI specifications and Postman exports, while outbound export generates request code in multiple languages and frameworks. The browser extension proxy for Chrome and Firefox routes requests through the user's browser to bypass CORS restrictions when testing localhost and internal APIs, with an alternative server-side proxy for headless environments. Single-file data import and export simplifies backup and migration between instances. The React and Vite frontend ships with dark mode enabled by default. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

MeterSphere is the open-source continuous testing platform that brings test management, API testing, and AI-powered automation into a single self-hosted environment. The Spring Boot Java backend handles test execution with the JMeter engine while the Vue.js frontend delivers a responsive interface for managing test cases, plans, defects, and reports across projects. The built-in AI assistant leverages large language models to auto-generate functional test cases and API interface definitions, reducing manual test creation effort. Test management covers the complete lifecycle from writing and reviewing cases in list or mind-map views, through test plan creation with single plans and plan groups, to defect tracking with customizable templates and workflow rules. API testing combines Postman-like ease of use with JMeter-level flexibility, supporting interface debugging with server-side and local execution, API definition with visual request and response editors, interface mocking with configurable headers and body parameters, scenario automation with visual orchestration, and detailed test reports with automatic generation. The system-organization-project hierarchy supports up to 30 users in the community edition with role-based access control, file management, and configurable notification channels. MySQL stores application data, Kafka handles message queuing, MinIO provides S3-compatible object storage, and Redis manages caching. The plugin marketplace extends testing capabilities and enables DevOps pipeline integration. On RepoCloud, deploy MeterSphere on a dedicated VPS with Docker, root SSH access, and complete control over your testing infrastructure, all under the GPLv3 license.

Fusio turns the data and services you already run into a managed API that partners, apps, and AI agents can actually use. The workflow starts small: add a database connection and a table becomes a REST endpoint, or proxy a remote service and route traffic between internal microservices. Each operation pairs an HTTP path with an action and a schema, so requests are validated and an OpenAPI specification plus client SDKs for major languages come out without extra effort. Custom behavior lives in reusable actions, and an AI assistant can draft actions and schemas from a plain-language prompt. Native Model Context Protocol support then offers those actions to autonomous agents as tools. Third-party developers get a self-service portal with documentation, testing tools, and their own keys. Every endpoint can be protected with scopes and rate limits. Asynchronous work runs through events, webhooks, cronjobs, and triggers. When the API becomes a product, plans, quotas, and transactions handle billing, and analytics follow usage, performance, and errors. A marketplace installs ready-made actions and apps, and the generator and test panels speed up development. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

A man-in-the-middle proxy you run on purpose, mitmproxy lets developers and testers inspect, edit, and replay HTTP and HTTPS traffic from any client. Point a browser, phone, or script at it and every HTTP/1, HTTP/2, HTTP/3, WebSocket, and TLS-protected connection appears as a flow you can open, search, and filter. Content views turn payloads from HTML to Protobuf into readable text. Intercept a request or response before it moves on, change its headers, body, or status by hand, then release it, or save the flow and replay it to the client or the server later. Map local and map remote rules answer requests with files or other URLs, while blocklists, anticache, sticky cookies, and proxy authentication cover routine test chores. Choose the interface that fits the job: a keyboard-driven terminal console, mitmweb in the browser with a Capture tab that sets up WireGuard devices with a QR code, or mitmdump for unattended logging in scripts. Proxy modes include regular, local capture, WireGuard, transparent, reverse, upstream, SOCKS5, and DNS. Addons written in Python add custom rewriting, recording, and automation. Teams use it for debugging, testing, privacy measurements, and penetration testing. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Convoy is an enterprise-grade webhooks gateway that manages both incoming and outgoing webhook traffic to guarantee reliable event delivery without exposing internal microservices to the public internet. Organizations deploy the platform at the edge to ingest events from message brokers such as Apache Kafka, RabbitMQ, and Google Cloud PubSub, or receive HTTP webhooks from third-party services directly. The gateway enforces delivery policies through configurable rate limiting per endpoint, circuit breaking during downstream outages, and automated retries using constant or exponential backoff with jitter. Developers can generate customer-facing webhook portals embedded via iframes, allowing end users to inspect delivery attempts, verify HMAC-SHA256 signatures, and manually replay failed events. Comprehensive security controls include static egress IP proxying to prevent server-side request forgery, automated rolling secret keys, and instant alerting via Slack or email when endpoints fail consecutively. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Elastic License 2.0 licensed.

A PostgreSQL database becomes a production-grade GraphQL API the moment Hasura GraphQL Engine points at it: track tables and relationships - existing schemas included - and full query, mutation, and subscription types appear with where, order_by, limit, offset, and on_conflict arguments, no resolvers or boilerplate written. Its Haskell core compiles GraphQL to efficient SQL, and any query becomes a real-time live query with a single keyword, powering dashboards and collaborative UIs over standard GraphQL subscriptions. Authorization is where Hasura earns its enterprise reputation: role-based access control with row- and column-level permission policies driven by session variables from JWTs, auth webhooks, or headers - each role effectively sees its own GraphQL schema containing only what it may touch, integrating cleanly with Auth0, Firebase, or homegrown auth. Event triggers fire webhooks on inserts, updates, and deletes for asynchronous business logic; Actions extend the schema with custom REST handlers; remote schema stitching merges external GraphQL services into one endpoint; and auto-generated REST endpoints serve clients that skip GraphQL. A browser console handles data modeling and API exploration, the CLI manages migrations and metadata as code, and deployment is a single stateless Docker container beside Postgres.

Unkey is the open-source platform that unifies API key management, rate limiting, deployment, and observability into a single control plane. The Go API service validates keys with sub-millisecond latency using regional Redis caches and MySQL 8.0 persistent storage, while ClickHouse captures every verification event for per-key and per-keyspace analytics with filterable time-series charts, request counters, and active key tracking. Keyspaces organize API keys by product, environment, or tier, each configurable with custom prefixes, byte lengths, IP whitelists, encrypted key recovery, and delete protection. Per-key settings include expiration dates, rate limit quotas with configurable windows, RBAC roles and permissions, owner identities linking multiple keys to a single user or organization, and key rotation with grace periods from immediate revocation through 24-hour overlap. The deployment pipeline connects GitHub repositories for automatic Docker container builds, generates preview environments per commit, promotes tested versions to production, and validates releases with OpenAPI diff detection flagging breaking changes before production. The edge gateway authenticates and rate-limits requests at the closest region before routing to the nearest API instance. Immutable audit logs track every key creation, verification, deletion, and configuration change with actor, timestamp, and event metadata. The CLI provides terminal access to key management, analytics queries, and deployment operations. On RepoCloud, deploy Unkey on a dedicated VPS with Docker, root SSH access, and complete control over your API infrastructure, all under the AGPL license.