Best Open Source API Testing Tools for Developers: Bruno vs Hoppscotch vs Insomnia Compared

Postman’s 2023 decision to remove its Scratch Pad and push users toward cloud-synced accounts triggered one of the loudest backlashes in developer tooling history. Within weeks, GitHub stars for open source alternatives spiked, and “Postman alternative” became a permanent search term. Two years later, three tools dominate that conversation: Bruno, Hoppscotch, and Insomnia. All three are open source. All three can send an HTTP request in under a minute. But they disagree on a fundamental question—where should your API collections actually live?—and that disagreement should drive your choice more than any feature checklist.

Why Developers Are Leaving Postman

The core complaints are consistent across Reddit threads, Hacker News posts, and GitHub issues:

• Account requirements. Postman now requires sign-in for basic functionality, and the lightweight Scratch Pad was deprecated in 2023.
• Cloud lock-in. Collections live on Postman’s servers by default, which raises questions for teams handling regulated or proprietary data.
• Resource usage. The Electron-based client is widely criticized for memory consumption on large workspaces.
• Pricing pressure. The free tier’s collaboration limits push growing teams toward paid plans.

The open source alternatives below address these concerns in different ways. None is a strict drop-in replacement for every Postman workflow, so it’s worth understanding each tool’s philosophy before migrating.

Bruno: Collections as Files on Disk

Bruno’s pitch is simple: your API collections are plain text files stored in a folder you choose, meant to be committed to Git alongside your code.

How it works. Each request is a .bru file with a human-readable syntax. Environments are separate files. There’s no cloud sync, no account, and no proprietary format. You open a collection by pointing Bruno at a folder—the same folder your teammates clone from your repository.

Strengths:

• Git-native workflow. Diffs and pull requests for API changes work exactly like code review. This alone wins over teams that treat API definitions as part of the codebase.
• Offline by default. Nothing leaves your machine unless you configure it to.
• Lightweight. Bruno uses a custom desktop shell rather than bundling a full browser runtime, and it feels noticeably snappier than Electron-based rivals on older hardware.
• Open source under MIT, with an active release cadence.

Trade-offs:

• No built-in cloud collaboration. If your team doesn’t use Git well, Bruno won’t fix that.
• The ecosystem of plugins and integrations is younger than Postman’s.
• The .bru format is Bruno-specific; migrating between tools requires conversion.

Bruno is the strongest choice for backend teams that already live in Git and want API tests versioned next to the services they exercise.

Hoppscotch: Browser-First and Fast to Adopt

Hoppscotch began as a web app you could open instantly without installing anything—originally called Postwoman—and that browser-first identity still shapes it.

How it works. You can use the hosted web client immediately, self-host the entire stack, or install a desktop app. It supports REST, GraphQL, WebSocket, SSE, and MQTT, which makes it unusually broad for a free tool.

Strengths:

• Zero-friction start. No install, no account required for basic use.
• Self-hosting. Teams with data residency requirements can run their own instance; the project is open source under MIT.
• Real-time protocol support. If you test WebSockets or GraphQL subscriptions, Hoppscotch handles them natively rather than as an afterthought.
• Clean, fast UI. The interface is minimal and keyboard-friendly.

Trade-offs:

• Collection management is less mature than Bruno’s file-based model or Postman’s workspace model.
• The desktop app historically lagged behind the web version in features.
• Heavy reliance on the browser means some advanced networking scenarios (custom certificates, certain proxy setups) can be fiddlier.

Hoppscotch suits developers who want to fire off requests fast, test real-time APIs, or self-host a shared instance without demanding deep Git integration.

Insomnia: The Mature Middle Ground

Insomnia has the longest history of the three and was acquired by Kong in 2019. That corporate backing cuts both ways, and it’s the source of the tool’s most contentious moment.

How it works. Insomnia offers a polished desktop client with strong support for REST, GraphQL, gRPC, and WebSockets. It introduced a local-only “Scratch Pad” mode and a design-first workflow for spec-driven development.

Strengths:

• Feature depth. GraphQL schema introspection, gRPC support, and plugin extensibility are more developed than in the other two.
• Design-first tooling. You can write an OpenAPI spec and generate requests from it, which appeals to teams practicing spec-driven development.
• Polished UX. For pure request-building ergonomics, many developers still rank Insomnia first.

Trade-offs:

• The 2023 account controversy. Insomnia briefly required accounts even for local use, prompting a community fork called Insomnium. Kong later restored a local-only mode, but trust took a hit.
• Licensing is more complicated. Insomnia moved to an MIT license in 2023 after earlier changes raised concerns, but the project’s direction is ultimately controlled by Kong, not the community.
• Heavier resource footprint than Bruno.

Insomnia makes sense if you need gRPC, deep GraphQL tooling, or spec-driven workflows and are comfortable with a vendor-backed project.

Head-to-Head Comparison

Dimension	Bruno	Hoppscotch	Insomnia
Storage model	Local files (Git-friendly)	Cloud or self-hosted	Local or cloud sync
License	MIT	MIT	MIT
Account required	No	No (for basic use)	No (local mode restored)
Protocol support	REST, GraphQL	REST, GraphQL, WS, SSE, MQTT	REST, GraphQL, gRPC, WS
Collaboration	Via Git	Built-in / self-hosted	Built-in (paid tiers)
Best for	Git-centric backend teams	Fast, browser-based testing	gRPC and spec-driven teams

Which Should You Choose?

• Choose Bruno if your team reviews code in pull requests and you want API collections treated the same way. It’s the cleanest answer to cloud lock-in.
• Choose Hoppscotch if you want to start testing in seconds, need real-time protocol support, or want to self-host a shared workspace.
• Choose Insomnia if gRPC, advanced GraphQL, or OpenAPI-driven design workflows are central to your work and you’re comfortable with Kong’s stewardship.

There’s no universal winner, and the migration cost between them is low enough that trying two for a week is a reasonable strategy. Export your existing Postman collections to OpenAPI where possible to keep your options open.

The Takeaway

The Postman exodus wasn’t really about features—it was about control over where API definitions live and who can access them. Bruno answers with files in your repo, Hoppscotch with a self-hostable web app, and Insomnia with a mature, vendor-backed client that now offers a local mode. Pick based on where you want your collections to reside and which protocols you actually test; the request-building experience across all three is good enough that storage philosophy, not button placement, is the deciding factor.