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Bun

Category: AI Developer Tools

Bun is an incredibly fast all-in-one JavaScript runtime, bundler, test runner, and package manager designed as a drop-in replacement for Node.js. Bun was founded in 2021. The company is led by Jarred Sumner. Based in San Francisco, United States. Team size: 14. Total funding raised: $26 million. Latest round: Series A ($19M, December 2025, led by Khosla Ventures and Andreessen Horowitz). Key investors include Khosla Ventures, Andreessen Horowitz, Kleiner Perkins, Y Combinator, Anthropic (strategic investor).

Founded
2021
Headquarters
San Francisco, United States
Team size
14
Total funding
$26 million

Value proposition

All-in-one JavaScript toolkit combining runtime, bundler, transpiler, task runner, and npm client. Uses JavaScriptCore engine instead of V8, delivering 3x faster performance than Node.js for server-side rendering, file operations, and HTTP requests. Drop-in replacement for Node.js with native TypeScript and JSX support.

Products and solutions

JavaScript runtime, Package manager (npm alternative), Bundler, Test runner, Transpiler, Task runner, Native TypeScript support, Native JSX support, Web API support

Unique value

Incredibly fast all-in-one JavaScript runtime and toolkit that combines runtime, bundler, test runner, and package manager in a single binary, delivering 3x performance improvements over Node.js.

Target customer

JavaScript developers, web developers, and teams seeking faster runtime performance and simplified tooling for JavaScript/TypeScript projects

Industries served

Developer Tools, Web Development, Backend Services, Full-Stack Development

Technology advantage

Uses Safari's JavaScriptCore engine instead of V8, enabling faster startup times and better performance. Handles 68,000 requests per second compared to 29,000 for Deno and 14,000 for Node.js. Three times faster at server-side rendering in React. Native TypeScript and JSX support without configuration.

How they differentiate

Bun differentiates by being an all-in-one solution (runtime, bundler, package manager, test runner) in a single binary, unlike Node.js which requires multiple tools. Uses JavaScriptCore instead of V8, delivering significantly better performance. Designed as a drop-in replacement for Node.js with better compatibility than Deno. Native TypeScript/JSX support out of the box.

Main competitors

Node.js, Deno

Key partnerships

Anthropic (acquirer; powers Claude Code/Agent SDK), Khosla Ventures (Series A lead), Andreessen Horowitz (Series A), Y Combinator (Seed), Kleiner Perkins (Seed), Midjourney (WebSocket scaling), Netflix, Spotify, KPMG, L'Oréal, Salesforce (via Claude Code)

Notable customers

Anthropic (Claude Code), Netflix, Spotify, KPMG, L’Oréal, Salesforce

Major milestones

$7M seed funding (Aug 2022), $19M Series A funding (Dec 2025), Bun 1.0 release (2024), 82,000+ GitHub stars, Acquisition by Anthropic (Dec 2025)

Growth metrics

82,000+ GitHub stars, 7M+ monthly npm downloads, active developer community

Market positioning

Positioned as the fastest JavaScript runtime and comprehensive toolkit for modern web development, targeting developers seeking performance improvements and simplified tooling.

Geographic focus

Global, open-source project with worldwide developer adoption

Patents and IP

No public patents or proprietary IP; fully open-source under MIT license.

About Jarred Sumner

Created Bun as an open-source project, then founded Oven.sh to commercialize it. Previously worked on JavaScript runtime development and performance optimization at Stripe and Facebook.

Official website: