Best alternatives to Thunder Client in 2026

When developers build an app that talks to a server, they constantly need to fire test requests at it — check that an endpoint returns the right data, that a login works, that an error is handled properly. Thunder Client is a tool that lets them do this directly inside the code editor they're already using, instead of switching to a separate app. Thunder Client is a REST API client extension for VS Code and JetBrains IDEs that lets developers test and debug APIs without leaving their editor. It supports REST, WebSocket, SSE and gRPC protocols, stores collections and test data locally on the machine (kept separate from any subscription account for privacy), and syncs collections across a team via a git repository rather than a proprietary cloud. A CLI enables running the same tests in CI/CD pipelines. With over 6 million downloads across 100+ countries, it's used from solo projects up to Fortune 500 companies and financial institutions. Paid tiers add secrets-manager integration (AWS, Azure), SSO, offline activation and performance testing for enterprise teams.