bun.sh/docs/runtime/web-apis.md

Some Web APIs aren't relevant in the context of a server-first runtime like Bun, such as the DOM API or History API. Many others, though, are broadly useful outside of the browser context; when possible, Bun implements these Web-standard APIs instead of introducing new APIs.

The following Web APIs are partially or completely supported.

{% table %}

---

• HTTP
• fetch Response Request Headers AbortController AbortSignal

---

• URLs
• URL URLSearchParams

---

• Web Workers
• Worker self.postMessage structuredClone MessagePort MessageChannel BroadcastChannel.

---

• Streams
• ReadableStream WritableStream TransformStream ByteLengthQueuingStrategy CountQueuingStrategy and associated classes

---

• Blob
• Blob

---

• WebSockets
• WebSocket

---

• Encoding and decoding
• atob btoa TextEncoder TextDecoder

---

• JSON
• JSON

---

• Timeouts
• setTimeout clearTimeout

---

• Intervals
• setInterval clearInterval

---

• Crypto
• crypto SubtleCrypto CryptoKey (X25519 curve support for crypto.subtle.generateKey())

---

• Debugging

• console performance

---

• Microtasks
• queueMicrotask

---

• Errors
• reportError

---

• User interaction
• alert confirm prompt (intended for interactive CLIs)

---

• Realms
• ShadowRealm

---

• Events
• EventTarget Event ErrorEvent CloseEvent MessageEvent

---

{% /table %}