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

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

Postman’s 2023 decision to remove the Scratch Pad and push users toward cloud-synced accounts triggered one of the loudest migrations the developer tooling world has seen in years. Within weeks, GitHub stars for alternatives spiked, and “Postman alternative” became a perennial search term. Three names keep surfacing in that conversation: Hoppscotch, Bruno, and Insomnia.

They are not interchangeable. One runs in your browser, one stores collections as plain files in your Git repo, and one has changed ownership and licensing in ways that matter. Here’s how they actually compare on architecture, features, licensing, and day-to-day workflow.

The Contenders at a Glance

	Hoppscotch	Bruno	Insomnia
Interface	Browser-based (PWA), desktop app available	Desktop app (Electron)	Desktop app (Electron)
Collection storage	Cloud (self-hostable) or local	Plain-text files on disk (.bru)	Local vault or cloud sync
License	MIT	MIT	MIT (core), with paid tiers
Git-friendly	Limited	Excellent	Limited
CLI/CI support	CLI available	bru CLI	Inso CLI
Best for	Quick requests, teams wanting a web UI	Git-centric teams, code review workflows	Users wanting a polished GUI with broad protocol support

Hoppscotch: The Browser-First Option

Hoppscotch started as a lightweight web app (originally called Postwoman) and still leads with that identity. Open hoppscotch.io, type a URL, hit send. No install, no account required for basic use. That zero-friction entry point is why it has attracted a large casual user base alongside its 60,000+ GitHub stars.

The tool covers the essentials well: REST, GraphQL, WebSocket, Server-Sent Events, MQTT, and Socket.IO. It handles environment variables, pre-request scripts, and test assertions. The desktop app exists for people who need to bypass browser CORS restrictions or work offline.

Where Hoppscotch gets interesting is self-hosting. Because the whole stack is MIT-licensed and open source, teams can run their own instance and keep request data on their own infrastructure—a genuine advantage for organizations with data residency requirements. The tradeoff is operational overhead: you’re now maintaining a service.

The browser-first design also has limits. Complex scripting feels cramped compared to desktop rivals, and the Git story is weak. Collections live in Hoppscotch’s workspace model rather than as files you can diff and review in a pull request.

Bruno: Collections as Code

Bruno made its name with a single architectural decision: collections are stored as plain-text files in a folder on your filesystem, using Bruno’s own .bru format. Point Bruno at a folder inside your Git repository, and your API collections become versioned artifacts like any other code.

This sounds minor. It isn’t. It means an API change can be reviewed in a pull request, a broken request can be caught in CI, and a new hire can clone the repo and immediately have the team’s full collection. There’s no export/import dance, no proprietary JSON blob, no cloud account required. Bruno’s tagline—“offline-only”—reflects a deliberate stance against mandatory sync.

Feature-wise, Bruno covers REST and GraphQL, environments, scripting (JavaScript), assertions, and a collection runner. The bru CLI lets you execute collections in pipelines, which is the piece most GUI-first tools handle awkwardly. Secrets management and a secrets manager integration exist for teams that need them.

The costs are real too. Bruno’s ecosystem is younger, so you’ll find fewer plugins and community templates. The UI is functional rather than beautiful. And if your team genuinely prefers a hosted, always-synced workspace, Bruno’s file-based model will feel like extra work rather than less.

Insomnia: Polished, But Read the Fine Print

Insomnia (originally by Kong) has the most mature interface of the three. It supports REST, GraphQL, gRPC, WebSocket, and GraphQL subscriptions, with a design-first workflow for spec-driven development. The Inso CLI handles CI integration, and the plugin ecosystem is the largest here.

The complication is licensing and ownership history. Insomnia’s core remains MIT-licensed, but the company has shifted its model over time—introducing paid tiers, requiring accounts for some features, and changing storage defaults. In 2023, Kong announced layoffs and Insomnia’s future direction became a topic of community speculation. The project was later acquired, and users have periodically raised concerns about telemetry and mandatory sign-ins.

None of this makes Insomnia unusable. It’s still a capable, well-maintained tool with strong protocol coverage. But if you’re choosing an open source tool specifically to avoid vendor lock-in and account requirements, Insomnia’s trajectory is worth weighing carefully. The MIT core is genuine; the surrounding product decisions are less predictable than Bruno’s or Hoppscotch’s.

Feature Comparison: What Actually Matters

Protocol support. Insomnia wins on breadth (gRPC, GraphQL subscriptions). Hoppscotch covers real-time protocols well. Bruno focuses on REST and GraphQL—sufficient for most teams, limiting for gRPC-heavy shops.

Scripting and testing. All three support JavaScript pre-request and test scripts. Insomnia’s is the most mature; Bruno’s is clean and adequate; Hoppscotch’s works but feels constrained in the browser.

Environments and secrets. All three handle environment variables. Bruno and Insomnia offer stronger secrets management; Hoppscotch relies on workspace-level variables unless self-hosted.

CI/CD. Bruno’s file-based model makes pipeline integration natural. Insomnia’s Inso CLI is capable but requires exporting collections. Hoppscotch’s CLI works but assumes connectivity to a workspace.

Collaboration. Hoppscotch and Insomnia offer hosted team features. Bruno’s collaboration model is Git itself—which some teams love and others find insufficient.

Which Should You Pick?

Choose Hoppscotch if you want instant access from any browser, value self-hosting for compliance reasons, or need a low-friction tool for ad-hoc testing across a team that doesn’t want to install anything.

Choose Bruno if your team lives in Git, reviews changes through pull requests, and wants API collections treated as first-class code. It’s the strongest fit for engineering organizations that already have CI pipelines and code review culture.

Choose Insomnia if you need the broadest protocol support, the most polished GUI, and don’t mind the account and licensing complexities. It remains the most feature-complete option of the three.

The Takeaway

The “best” tool here depends less on feature checklists than on where you want your API collections to live. Hoppscotch puts them in a workspace you can self-host, Bruno puts them in your repository as files, and Insomnia puts them in a polished app with a cloud component. If avoiding lock-in is your priority, Bruno’s plain-file approach is the most durable bet; if convenience and protocol breadth matter more, Hoppscotch and Insomnia each make a reasonable case. Try all three against one real project before committing—the migration cost later is higher than the hour it takes now.