Vulcain

Judgement

What it is

Building block

What it does

A protocol and Caddy-based gateway that lets clients ask a REST API to preload related resources with Preload hints and 103 Early Hints, as an alternative to GraphQL-style compound requests.

Adopt it when

You run a REST API with many linked resources, such as one built on API Platform, and want clients to fetch related data without over-fetching.

Watch out

Browsers dropped HTTP/2 server push, which weakened the original design, and adoption outside the API Platform community is small; it is AGPL-licensed.

Ready for

Usable

Runs as

Self-hosted server and library

Built with

Go and Caddy

How established

Established: started 7 years ago, latest release v1.4.5.

What the license allows

Use inside your business is unrestricted. If you change it and let customers use it over the internet, you must publish your changes.

Judged on 2026-11-06 from the project's README and GitHub data. The license and age lines are worked out directly.

Built from

Follow it down: Vulcain → Go → runs on a microchip

How compilers were built, back to punched paper tape

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