Merkur

The Merkur is tiny extensible javascript library for front-end microservices(micro frontends). It allows by default server side rendering for loading performance boost. You can connect it with other frameworks or languages because merkur defines easy API. You can use one of six predefined template's library Preact, µhtml, Svelte and vanilla but you can easily extend for others.

Features

• Flexible templating engine
• Usable with all tech stacks
• SSR-ready by default
• Easy extensible with plugins
• Tiny - 1 KB minified + gzipped

Getting started

npx @merkur/create-widget <name>

cd name

npm run dev // Point your browser at http://localhost:4444/

Documentation

To check out live demo and docs, visit https://merkur.js.org.

Contribution

Contribute to this project via Pull-Requests.

We are using Changesets for versioning and releasing. To add a changeset describing your changes, run npm run changeset.

Note: The release process is documented only in this root README. Any per-package README sections that still describe a Lerna/Conventional Commits–based release flow are outdated and should be ignored in favour of the instructions below.

Changeset format

Each changeset file (.changeset/*.md) must follow this structure:

Frontmatter — standard Changesets YAML listing affected package names and bump types (patch, minor, major).

First line after frontmatter — a single brief sentence summarising the change. No heading, no bold, no trailing bullet — just a plain declarative sentence. This section is not required but helps to quickly understand the change when browsing the changesets.

Body — three bullet points in this exact order, with no blank lines between them:

• What One or more sentences describing what changed: which APIs, files, or behaviours were added, removed, or fixed. Make sublists if needed to break down complex changes, but keep each bullet point as a single paragraph.
• Why One or more sentences explaining the motivation: why the change was necessary or beneficial.
• How Migration steps for consumers or contributors. If no action is required, write exactly: Nothing.

Additional rules:

• Each bullet is a single paragraph — no nested lists, no code blocks inside a bullet.
• Do not use headings (##, ###) inside the body.
• Code symbols (function names, paths, package names) use backtick inline code.

Example:

---
"@merkur/example": minor
---

Add `createFoo` helper for simplified widget initialisation.

- **What** New `createFoo(options)` export in `@merkur/example` wraps the low-level `initFoo` call and applies sensible defaults for `name` and `version`.
- **Why** Every project was duplicating the same boilerplate to call `initFoo`; centralising it reduces setup friction and ensures consistent defaults.
- **How** Replace direct `initFoo` calls with `createFoo({ name, version })`. The returned object is API-compatible, so no further changes are needed.

Release

To release a version you must have the right permissions, please contact one of the repo maintainers.

Regular version release

To do a regular release, from the master branch with no uncommitted changes, run:

npm run release

This runs release:prepare (applies pending changesets, bumps versions, updates package-lock.json) followed by release:push (commits, tags, and pushes to the repository).

Packages are published from a GitHub Action triggered when a new version tag is pushed.

RC (pre-release) release

1. Enter pre-release mode (only needs to be done once per RC cycle):

   npm run release:next:init
   

   This sets pre-release mode to rc, so subsequent version bumps produce rc versions (e.g. v0.44.0-rc.0).

2. Add a changeset describing your changes:

   npm run changeset
   

3. Bump versions and push the RC release:

   npm run release
   

   Repeat steps 2–3 for each subsequent RC iteration (e.g. rc.0 → rc.1).

4. When ready to graduate to a stable release, exit pre-release mode and prepare the final version:

   npm run release:graduate
   

   Then push with:

   npm run release:push
   

Thank you to all the people who already contributed to Merkur!