Corsair: A REST-Based Integration Layer for Agents and Multi-Tenant Dashboards

The Glue Code Problem Corsair Targets

Every third-party API an agent touches brings its own authentication flow, its own pagination convention and its own error shapes. The README states the goal plainly: "The more third-party APIs your agent touches, the more glue code you write." Corsair's answer is a single syntax across integrations, with the adapters maintained upstream rather than in your codebase. The intended audience is narrow and specific. It is not a general HTTP client. It is for teams building a product where the same integration surface has to serve three consumers at once: an agent calling functions, a backend service running scheduled work, and a dashboard where your own users connect their accounts. That last consumer is what separates Corsair from most agent tooling. A multi-tenant dashboard needs per-user OAuth tokens, a connection state to render, and a way to revoke access. A single-user agent script needs none of that.

REST Instead of MCP, and Why That Choice Matters

The README makes the architectural claim directly: "Most agent integration tools are MCP-only. Corsair is built on a REST API, so the same integration layer works for agents, backend services, and the dashboards your customers use." This is the core design decision and it has consequences in both directions. A REST surface is callable from a browser, from a serverless function, from any language with an HTTP client, and from an agent runtime that speaks HTTP. An MCP server is callable from MCP clients. If your product is an MCP client and nothing else, the REST layer is an extra hop. If your product is a web application that also happens to run an agent, the REST layer is the only one of the two that your frontend can talk to directly. The repository lists mcp among its topics, so MCP is not excluded, but the README does not describe an MCP server implementation. Treat the MCP relationship as unconfirmed from the supplied material.

Self-Hosting, Managed OAuth and the Hub Split

Corsair is offered in two modes. The README says you can "Self-host it, or use Hub if you want us to handle OAuth refresh and webhooks." That sentence is the most operationally important one in the document, because it tells you what the managed tier actually sells. OAuth refresh and webhook delivery are the two parts of an integration platform that fail silently in production. A refresh token that expires at 3am breaks every scheduled job for that user. A webhook endpoint that misses a delivery leaves your data stale with no error surfaced anywhere. Self-hosting means you own both of those failure modes. The README's framing of the open source option is about data custody: "Closed integration platforms keep your users' tokens and data on infrastructure you can't inspect or leave." That is a real distinction, and it is also a real cost. Running your own token store means running your own encryption, rotation and audit story for it.

What the Repository Actually Documents About Setup

This is where the material runs out. The README contains no installation command, no configuration keys, no code example, and no API reference. It links to the website and to a YouTube demo, and it points contributors at CONTRIBUTING.md for the workflow. The only concrete artifact named in the repository listing is the npm package corsair, and the only release is v0.1.0, dated 2025-12-05. The npm badge in the README links to a download chart, which tells you the package is published, not how it is used. If you want to evaluate Corsair today, the honest path is to read the source on the main branch and inspect the package exports, because the README will not get you to a running instance. Any article that shows you a corsair.init() call and a config object is inventing it. I am not going to do that.

The Version Number Is the Main Risk Signal

v0.1.0 is the first release, published in December 2025, and the repository's last push is dated 2026-09-10. That combination means the project is under active development and has not yet reached a version where interface stability is a reasonable expectation. For an integration layer this matters more than it would for a utility library, because your integration code is the part of your product that touches customer credentials. A breaking change in how a connection is represented or how a token is retrieved is not a rename you fix in an afternoon. The README's contribution section invites PRs for "the core library, docs, tooling, and new integration plugins," and asks contributors to claim a new integration on the OSS Integrations page before starting. That is a reasonable process, and it also confirms that the adapter set is being built out incrementally. Before you plan around a specific integration, check whether its adapter exists in the repository.

Where Corsair Is the Wrong Tool

If you are building a single-user agent that needs one or two APIs and runs on your own machine, Corsair adds a layer you will spend time learning and no time benefiting from. The multi-tenant dashboard story, the per-user connection state, the OAuth refresh handling, none of it applies. Write the API calls directly. The same applies if your entire product is an MCP server. The README's argument against MCP-only tools is that they cannot serve a dashboard, and if you have no dashboard, that argument does not reach you. There is a third case: teams that need a documented, versioned API contract with a deprecation policy. Corsair at v0.1.0 does not offer that, and the README does not claim to.

The Alternative: Composio and the Managed-First Approach

The closest well-known alternative in this space is Composio, which also targets agents that need to call third-party tools with managed authentication. The difference in approach is where the integration logic lives. Composio's model centres on tool definitions that an agent framework consumes, with the platform handling auth and execution on its infrastructure. Corsair's model centres on a REST API that your own services call, with self-hosting as a first-class option and the managed Hub as an add-on for OAuth refresh and webhooks. If your agent framework already speaks a tool-calling protocol and you want the integration vendor to own the runtime, the managed-first model is less code. If you need your frontend to talk to the same integration layer your agent uses, or you need the tokens to stay on infrastructure you control, Corsair's REST-and-self-host split is the more direct fit. The two are not interchangeable, and the choice comes down to whether the dashboard is a first-class consumer or an afterthought.

Licence Metadata and What to Check Before Adopting

The repository listing reports the licence as NOASSERTION, which is GitHub's label for a licence file it could not classify automatically. The README states the project is "Licensed under the Apache License, Version 2.0" and links to the LICENSE file. Those two signals disagree, and the README is the one making a claim. The practical step is to open the LICENSE file on the main branch and read it, rather than trusting either the badge or the README paragraph. Apache-2.0, if that is what the file contains, permits commercial use and modification and includes a patent grant, with the usual requirements around attribution and notice retention. That is a permissive arrangement, but it is not legal advice and the terms that apply to you depend on how you distribute your product. The NOASSERTION label is worth resolving before you build a commercial product on top of the library, because the answer changes what you can ship.

Editorial conclusion

Adopt Corsair if you are building a TypeScript product where agents, backend jobs and a customer-facing connection dashboard must share one integration layer, and you are willing to read the source because the README does not document the API. Do not adopt it if you only need MCP tooling for a single agent, or if you require a stable interface with a documented migration path. Before committing, verify three things: the actual contents of the LICENSE file against the Apache-2.0 claim, the exported symbols in the npm package, and whether the adapters you need exist in the repository rather than only on the website.

Official sources

1. corsairdev/corsair on GitHub
2. Issues
3. Project website
4. README
5. Releases