Comparison

Bullet versus Re.Pack and Rollipop

This page compares Bullet's development server against two mature React Native bundler toolkits: Re.Pack, built on webpack and Rspack, and Rollipop, built on Rolldown. All three aim to be drop-in replacements for Metro's dev server, so they preserve the HTTP and WebSocket surface that React Native clients, symbolication, and the debugger expect.

The goal here is to be honest about what Bullet already matches, what remains a genuine gap, and which gaps are deliberate design differences.

Architecture at a glance

The three tools share the Metro-compatible surface but diverge sharply in how the server is packaged and what it exposes.

Aspect	Bullet	Re.Pack	Rollipop
Server model	Embedded in H3 via a `bullet()` plugin	Standalone `@callstack/repack-dev-server`	Integrated `createDevServer()`
HTTP layer	H3 and crossws	Fastify 5	Fastify 5
Bundler	Rspack	webpack or Rspack	Rolldown
Multi-platform	One in-process `MultiCompiler`	Rspack `MultiCompiler`; webpack worker pool	One engine per `(bundle, id)` in a static pool
Output storage	In-memory	In-memory (memfs)	On disk plus a native transform cache
Unique strength	Streaming React Native Web SSR	Bundler-agnostic delegate; Module Federation	Event-bus observability: SSE, MCP, dashboard

Bullet's streaming SSR of React Native Web, evaluated from a Node VM server bundle, is something neither Re.Pack nor Rollipop offer.

What Bullet does well

These capabilities are on par with both reference servers, so they aren't gaps.

Metro-compatible bundle URL scheme (/index.bundle?platform=) that returns application/javascript.
multipart/mixed bundle progress streaming, so the React Native client shows a live bundling progress bar on cold builds.
Metro and security response headers: X-React-Native-Project-Root, X-Content-Type-Options: nosniff, and Access-Control-Allow-Origin: devtools://devtools on source-map responses.
POST /symbolicate with a symbolicator that derives the source-map name from the request stack frames instead of assuming a fixed entry name.
Source-map serving with the correct DevTools CORS header.
Asset serving under /assets/*.
Wait-for-compile-then-serve semantics, so requests that arrive mid-build queue instead of returning a 404.
Web HMR with React Refresh, plus native HMR status broadcast.
A native in-app console log socket at /__client that surfaces console.* output from the device.
A WebSocket heartbeat that pings every 30 seconds and terminates dead peers.
Reuse of the real @react-native-community/cli-server-api and @react-native/dev-middleware, so /status, /message, /events, the dev menu, and the Fusebox inspector all work.
A local terminal dashboard with reload, dev-menu, and debugger shortcuts.
An offline bundle command.

Gaps

These features exist in one or both reference servers but not in Bullet. Most are about extended tooling and observability rather than core Metro compatibility.

Gap	Present in	Notes
HTTPS and TLS	Re.Pack	The dev server runs over HTTP only.
Build-stats HTTP or WebSocket API	Re.Pack, Rollipop	No `platforms`, `assets`, or `stats` endpoints.
Central event bus	Rollipop	Events bridge to the CLI, not a unified bus.
Server-sent event streams	Rollipop	No `/sse/*` streams for external subscribers.
Browser dashboard and REST API	Rollipop	Only a local terminal dashboard exists.
MCP server	Rollipop	No Model Context Protocol endpoint for agents.
Module Federation CDP resource loading	Re.Pack	No Module Federation story.

Re.Pack-specific gaps

A bundler-agnostic Server.Delegate interface, so the server never imports a bundler. Bullet is coupled to Rspack by design.
CDP interception that loads cross-origin Module Federation remotes into DevTools.
A REST and WebSocket tooling API that pushes build events and exposes platform, asset, and compilation stats.

Rollipop-specific gaps

A built-in MCP server that exposes build logs, client logs, and symbolication to AI agents.
Server-sent event streams that feed an external dashboard.
A browser dashboard backed by a rich REST API and a persisted build-state model.
A central event bus that routes reporting and HMR through one correlated stream.
Push-based HMR, where the server sends prebuilt module code. Bullet uses the conventional signal-based model, where the client computes and applies the update.

Summary

Bullet has solid core parity with both reference servers. It matches the Metro-compatible surface that mattered most: multipart/mixed progress streaming, the Metro and security headers, an explicit source-map response with DevTools CORS, a request-aware symbolicator, the /__client console log socket, and a WebSocket heartbeat. On top of that, it offers streaming React Native Web SSR that neither reference server has.

The remaining gaps are mostly about extended tooling. HTTPS and a build-stats API are the most portable additions. The observability features, that is, a central event bus, server-sent event streams, a browser dashboard, and an MCP server, are higher-effort and optional. Pursue them only if developer-experience tooling or AI-agent integration is a product goal.