JavaScript provides native SHA hashing via the Web Crypto API (SubtleCrypto.digest). For MD5, you need a library or custom implementation. This guide covers both browser and Node.js approaches with working code examples.
Frontend developers need hashing for file integrity checks, content fingerprinting, caching keys, and client-side data verification. Backend (Node.js) developers use hashing for authentication, checksums, and API signing.
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How to Generate Hash in JavaScript — Web Crypto API Guide
- Browser SHA-256: crypto.subtle.digest("SHA-256", data)
- Convert ArrayBuffer to hex string for display
- Node.js: const crypto = require("crypto"); crypto.createHash("sha256").update(text).digest("hex")
- For MD5 in browser: use a library (no native support)
- For file hashing: read as ArrayBuffer with FileReader first
- Test your hash output with our free tool above
Pro Tips
- Web Crypto API supports: SHA-1, SHA-256, SHA-384, SHA-512 (not MD5)
- SubtleCrypto.digest() is async — use await or .then()
- For Node.js: crypto module supports MD5, SHA-1, SHA-256, SHA-512 natively
- To hash files in browser: use FileReader.readAsArrayBuffer() → crypto.subtle.digest()
Frequently Asked Questions
How to SHA-256 hash in the browser?
const hash = await crypto.subtle.digest("SHA-256", new TextEncoder().encode(text)); then convert the ArrayBuffer to hex. Web Crypto API is available in all modern browsers.
Does JavaScript support MD5 natively?
Browser: No, Web Crypto API does not include MD5 (deprecated). Use a library like spark-md5. Node.js: Yes, crypto.createHash("md5").update(text).digest("hex") works natively.
Is Web Crypto API synchronous or async?
Async. crypto.subtle.digest() returns a Promise resolving to an ArrayBuffer. Use await or .then() to get the result.
How to hash a file in JavaScript?
Read the file with FileReader.readAsArrayBuffer(), then pass the ArrayBuffer to crypto.subtle.digest("SHA-256", buffer). Works for files of any size in modern browsers.
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