The API Testing Tool Built for Speed, Privacy, and Reliability
RESTK is a native, offline-first, privacy-first API testing tool. Test REST, GraphQL, WebSocket, and SSE APIs with AES-256 encryption and local-first storage. No Electron, no forced cloud sync, no account required.
Why Developers Choose RESTK
Most API testing tools are Electron apps that require cloud accounts and send your data to external servers. RESTK takes a fundamentally different approach.
Native Performance
Built with SwiftUI on macOS and native APIs on Windows. No Electron overhead, no Chromium wrapper. RESTK launches in under a second and uses a fraction of the memory that browser-based tools consume.
Offline-First
Every feature works without an internet connection. Local-first storage means your collections, environments, and history are always available, whether you are on a plane, in an air-gapped lab, or simply offline.
Privacy-First
AES-256 encryption at rest. Your API keys, tokens, and request payloads never leave your machine unless you explicitly choose to sync. No telemetry, no third-party data processing, no forced cloud accounts.
MCP Integration
Local AI-powered workflows via Model Context Protocol. Connect your AI assistants to RESTK for intelligent request building, response analysis, and automated test generation. All processing stays on your machine.
Nova Scripting
Powerful scripting framework for test automation with pre-request and post-response scripts. Write assertions, chain requests, extract variables, and build complex API testing workflows with a clean, modern API.
Import Everything
Import from Postman, Insomnia, OpenAPI specifications, HAR files, and cURL commands. Migrate your existing API collections to RESTK in seconds without losing folder structure, variables, or scripts.
What You Can Test with RESTK
RESTK supports every major API protocol and authentication method. Build, send, and inspect requests for any API type from a single native application.
REST APIs (GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS)
GraphQL queries and mutations
WebSocket connections
Server-Sent Events (SSE)
SOAP/XML APIs
File upload/download APIs
OAuth 2.0 / JWT authentication flows
How It Works
Get started with API testing in under a minute. No account creation, no cloud setup, no configuration files.
Download RESTK
Install the native app for macOS or Windows. No account required, no sign-up flow, no credit card. Open the app and start working immediately.
Create a Request
Build your API request with the visual editor. Set the method, URL, headers, query parameters, and body. Organize requests into collections and folders.
Execute and Inspect
Send the request and inspect the response in detail. View headers, body, timing data, status codes, and size. Compare responses across multiple executions.
Automate with Scripts
Write pre-request and post-response scripts using the Nova scripting engine. Chain requests, extract variables, run assertions, and build end-to-end API test suites.
RESTK vs Postman vs Insomnia
See how RESTK compares to the most popular API testing tools on the features that matter most to developers.
| Feature | RESTK | Postman | Insomnia |
|---|---|---|---|
| Native app (not Electron) | |||
| Offline-first architecture | |||
| Free to use | |||
| Privacy-first (AES-256) | |||
| MCP integration | |||
| No account required | |||
| Local-first storage | |||
| Import from Postman |
Want a detailed comparison? See RESTK as a Postman alternative
Frequently Asked Questions
Common questions about API testing and RESTK.
What is API testing?
API testing is the process of verifying that application programming interfaces work correctly, reliably, and securely. It involves sending requests to API endpoints, inspecting responses, and validating that the data, status codes, headers, and performance metrics meet expectations. API testing covers functional testing, integration testing, performance testing, and security testing of REST, GraphQL, WebSocket, and other API protocols.
Is RESTK free?
Yes, RESTK is free to download and use. The core API testing features, including sending requests, organizing collections, writing test scripts, and working offline, are available at no cost. There is no trial period, no feature gating, and no account required. Premium team features like encrypted cloud sync and team workspaces are available through paid plans.
Does RESTK work offline?
Yes, RESTK is built offline-first. Every feature works without an internet connection, including creating and editing requests, managing collections and environments, running test scripts, and viewing request history. Your data is stored locally on your machine and never requires cloud connectivity to access.
Can I import my Postman collections?
Yes, RESTK supports importing Postman collections (v2.0 and v2.1), including requests, folders, environments, and variables. You can also import from Insomnia, OpenAPI/Swagger specifications, HAR files, and cURL commands. The import process preserves your folder structure, environment variables, and request configurations.
What platforms does RESTK support?
RESTK is available as a native application for macOS (built with SwiftUI) and Windows (built with native APIs). Both versions deliver full native performance without Electron or browser-based wrappers. RESTK supports macOS 13 (Ventura) and later, and Windows 10 and later.
Learn More About API Testing
Explore guides, comparisons, and best practices for API testing with RESTK.
Ready to test APIs the way they should be tested?
Download RESTK and experience native performance, offline-first reliability, and privacy-first security. Free to start, no account required.