No direct Primer3 API replacements listed yet
Open-source API tools. To compare with Primer3 API.
47 open-source API tools
Hoppscotch
API Tools
Helps you create requests faster, saving precious time on development.
MITvs Postmanβ 81k
Bruno
API Tools
Bruno is the Git-native API client for REST, GraphQL, gRPC and Websocket. A local and open
MITvs Postmanβ 47k
Kong
API Tools
π¦ The API and AI Gateway
Apache-2.0vs Apigeeβ 44k
Insomnia
API Tools
The open-source, cross-platform API client for GraphQL, REST, WebSockets, SSE and gRPC. Wi
Apache-2.0vs Postmanβ 40k
Hasura
Backend as a Service
Blazing fast, instant realtime GraphQL APIs on all your data with fine grained access cont
Apache-2.0vs AWS AppSyncβ 32k
OpenAPI Generator
API Tools
OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs
Apache-2.0vs Stainlessβ 27k
Yaak
API Tools
The most intuitive desktop API client. Organize and execute REST, GraphQL, WebSockets, Ser
MITvs Postmanβ 19k
Apache APISIX
API Tools
The Cloud-Native API Gateway and AI Gateway
Apache-2.0vs Apigeeβ 17k
Scalar
API Tools
Scalar is an open-source API platform:γγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγπ Modern RES
MITvs Postmanβ 16k
OpenWA
API Tools
OpenWA - The free, open source WhatsApp API Gateway with a pluggable architecture. Self-ho
MITvs Twilioβ 15k
Nango
API Tools
Connect your agents & product to 1,000 APIs.
OSSvs Mergeβ 13k
Tyk
API Tools
Open Source API and AI Gateway supporting REST, GraphQL, TCP, gRPC and MCP (Model Context
OSSvs Apigeeβ 11k
Higress
API Tools
π€ AI Gateway | AI Native API Gateway
Apache-2.0vs Amazon API Gatewayβ 9.5k
Karate
Testing & QA
Test Automation Made Simple
MITvs Postmanβ 9k
Mockoon
API Tools
Mockoon is the easiest and quickest way to run mock APIs locally. No remote deployment, no
MITvs Beeceptorβ 8.4k
Newman
API Tools
Newman is a command-line collection runner for Postman
Apache-2.0β 7.3k
Requestly
API Tools
Community hub for Requestly API Client β bugs, feature requests, and roadmap. The privacy-
OSSvs Postmanβ 6.8k
Unkey
API Tools
The Developer Platform for Modern APIs
OSSvs Zuploβ 5.5k
pREST
Backend as a Service
PostgreSQL β REST, low-code, simplify and accelerate development, β‘ instant, realtime, hig
MITvs Firebaseβ 4.6k
Cortex Docs
API Tools
Cortex - Generates interactive API documentation, typed SDKs, and MCP servers from OpenAPI
MITvs Mintlifyβ 3.2k
API Dash
API Tools
API Dash is a beautiful AI-powered open-source cross-platform (Desktop & Mobile) API Clien
Apache-2.0vs Postmanβ 2.9k
DummyJSON
API Tools
DummyJSON.com provides different types of REST Endpoints filled with JSON data which you c
OSSvs Mockarooβ 2.9k
Restfox
API Tools
Offline-First Minimalistic HTTP & Socket Testing Client for the Web & Desktop
MITvs Postmanβ 2.8k
KrakenD
API Tools
KrakenD Community Edition: High-performance, stateless, declarative, API Gateway written i
Apache-2.0vs Amazon API Gatewayβ 2.7k
Insomnia Mockbin
API Tools
Insomnia Mockbin is the underlying backend for the API mocks capability of Insomnia. It is
OSSvs Beeceptorβ 2.1k
Resterm
API Tools
Terminal API client for HTTP, GraphQL and gRPC. Plain .http files you can diff and version
Apache-2.0vs Postmanβ 2k
Voiden
API Tools
Design, Test and Document APIs in plain Markdown. Compose Requests with API blocks. Reuse,
Apache-2.0vs Postmanβ 1.9kATAC
API Tools
A simple API client (postman like) in your terminal
MITvs Postmanβ 3.7kZato
Workflow Automation
ESB, SOA, REST, APIs and Cloud Integrations in Python
AGPL-3.0vs MuleSoftβ 1k
AnythingMCP
AI Infrastructure
Open-source, self-hosted MCP gateway: turn any REST/OpenAPI, SOAP, GraphQL, OData or SQL A
AGPL-3.0β 948
Chapar
API Tools
Chapar is a simple and easy to use api testing tools aims to help developers to test their
BSD-3-Clausevs Postmanβ 714curlie
API Tools
The power of curl, the ease of use of httpie.
MITβ 3.7kROAPI
API Tools
Create full-fledged APIs for slowly moving datasets without writing a single line of code.
Apache-2.0β 3.4k
CodeChat
API Tools
CodeChat - WhatsApp Api
Apache-2.0vs Twilioβ 1.3k
RustMailer
Email Clients & Servers
A self-hosted Email Middleware for IMAP, SMTP, Gmail API, Graph API β built for developers
OSSvs Nylasβ 513
Firecamp
API Tools
Developer-first OpenSource API DevTool, Postman/Insomnia alternative.
AGPL-3.0vs Postmanβ 2.6k
HTTPie CLI
API Tools
π₯§ HTTPie CLI β modern, user-friendly command-line HTTP client for the API era. JSON supp
BSD-3-Clausevs Postmanβ 39k
Notion API Worker
CMS
Notion as CMS with easy API access
OSSvs Superβ 1.7kApiArk
API Tools
Privacy-first API platform built with Tauri v2. No login, no cloud, ~60 MB RAM. A lightwei
MITvs Postmanβ 1.3k
DBAPI
API Tools
Build rest API with SQL in one minute
AGPL-3.0β 801Ain
API Tools
A HTTP API client for the terminal
MITvs Postmanβ 620
HTTPie Desktop
API Tools
π HTTPie Desktop β cross-platform API testing client for humans. Painlessly test REST, Gr
OSSvs Postmanβ 4k
Orange API Gateway
API Tools
OpenResty/Nginx Gateway for API Monitoring and Management.
MITvs Apigeeβ 2.3k
Mocky
API Tools
Generate custom HTTP responses, the simpler way to test your Web Services
Apache-2.0vs Beeceptorβ 2.1k
Step CI
Testing & QA
Automated API Testing and Quality Assurance
MPL-2.0vs Postmanβ 1.9k
VulcanSQL
API Tools
Data API Framework for AI Agents and Data Apps
Apache-2.0vs Tinybirdβ 793DataFire
Workflow Automation
A framework for building integrations and APIs
MITvs Zapierβ 575
