sync-sha256

Zero-dependency, synchronous SHA-256 for TypeScript. Drop-in replacement for js-sha256 with first-class type safety.

Demo

• No dependencies — pure TypeScript, no crypto polyfills
• Synchronous — no await, works in sync contexts
• UTF-8 — correct handling of Unicode, including surrogate pairs (emoji, CJK)
• Zero allocations on repeated calls (reuses internal Uint32Array)
• Tree-shakeable — only import what you use

Install

npm install sync-sha256
# or
bun add sync-sha256

Usage

import { sha256 } from 'sync-sha256'

sha256('') // e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
sha256('The quick brown fox jumps over the lazy dog') // d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592

// UTF-8
sha256('中文') // 72726d8818f693066ceb69afa364218b692e62ea92b385782363780f47529c21
sha256('🎉')   // 6146299cd54818a0e659eb6ac88e80f6f8f70536bbbd962d36973f2d2323f26c

API

sha256(message: string): string

Returns a 64-character hex string.

import { sha256 } from 'sync-sha256'

const hash = sha256('Message to hash')
// => 'f7bc83f430538424b13298e6aa6fb1438f4d89a51f0ed5d0a63f5b3e1230c20e'

Differences from js-sha256

| Package | Size | SHA-224 | HMAC | Streaming | | ----------- | ------ | ------- | ---- | --------- | | js-sha256 | ~3.5KB | ✅ | ✅ | ✅ | | sync-sha256 | ~2KB | ❌ | ❌ | ❌ |

Use js-sha256 if you need SHA-224, HMAC, streaming, or byte array input.

Use sync-sha256 if you need a smaller, typed, synchronous string-to-hex hasher.

Benchmarks

Bun 1.3.2, AMD Ryzen 5 7500F:

| Test | Throughput | Time | | ---------------------------------- | ----------------- | ----- | | 100K × 5-byte strings | 929K ops/sec | 108ms | | 10K × 100-byte strings | 610K ops/sec | 16ms | | 1K × 10KB strings | 11.1K ops/sec | 91ms | | 100 × 1MB strings | 117 ops/sec | 862ms | | Sustained throughput (50MB chunks) | 108 MB/s | 443ms | | Single 500MB string | — | 5.0s | | 2K × 1MB strings (2GB total alloc) | — | 17.7s | | Single 1GB string (doubling) | — | 9.7s |

License

MIT