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Bun

San Francisco, US · founded 2019 · ≈18 (May 2026) employees · Software Publishers · bun.sh

Bun is an MIT-licensed JavaScript and TypeScript toolkit built on JavaScriptCore. It combines a runtime, package manager, bundler and test runner. Its creator Jarred Sumner released version 1.0 in September 2023. Its company, Oven, raised a $7M seed round led by Kleiner Perkins in 2022. Sumner said in Dec 2025 that the company had raised $26M in total and made $0 in revenue. The planned monetization was hosting. Anthropic acquired it in December 2025 (its first acquisition), and Claude Code uses Bun. Anthropic said Bun will stay open source.

Developer ToolsJavaScript RuntimeOpen SourceAI Coding Infrastructure

Funding

1
Every round, secondary, debt facility or acquisition involving Bun that AI Lounge tracks, newest first. Latest: Acquisition on Dec 2, 2025.
Bun logo
Bundetails →AcquisitionDec 2
Anthropic (acquirer) · Developer tools
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Timeline · 3

Oct 5, 2026
Deal
Ukraine's Buntar Aerospace raises $16M for GPS-denied reconnaissance drones and its AI copilot · Tech.eu
Dec 2, 2025
Round
Acquisition · Anthropic
Dec 2, 2025
Deal
Anthropic buys Bun, the JavaScript runtime Claude Code runs on · Anthropic

In the news

2
Ukraine's Buntar Aerospace raises $16M for GPS-denied reconnaissance drones and its AI copilot2026-10-05Anthropic buys Bun, the JavaScript runtime Claude Code runs on2025-12-02
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