SHA-256 Hash Generator

Encrypt any text or file to SHA-256, or try to reverse a known SHA-256 hash with the built-in dictionary. 100% client-side via the Web Crypto API.

About SHA-256

SHA-256 is a member of the SHA-2 family, designed by the NSA and published in 2001. It produces a 256-bit (64-character hexadecimal) digest and is currently the industry standard for cryptographic hashing. It is the algorithm behind Bitcoin mining, TLS/SSL certificates, JWT signing, SSH host fingerprints, and modern password salting. No practical collision attack is known, and it remains the recommended default for new code that needs a secure hash.

How to Use

Encrypt: switch to the Text Input or File Input tab, type / paste text or drop a file, then click Generate SHA-256.
Reverse lookup: switch to the Decrypt (Dictionary) tab, paste the target SHA-256 hash, and start the dictionary attack. Note: SHA-256 has a huge output space, so only short / common plaintexts are recoverable.
Copy: click the copy icon to copy the hash to your clipboard.

FAQ

Can SHA-256 be decrypted?

SHA-256 is one-way and cannot be reversed mathematically. The dictionary attack here tries every candidate in your wordlist, hashing each one with SHA-256 and comparing to the target. This is useful only for short, common, or predictable plaintexts — long random passwords are infeasible to recover.

How to verify a SHA-256 checksum on Windows / Mac / Linux?

Windows (PowerShell): Get-FileHash .\file.zip -Algorithm SHA256
macOS: shasum -a 256 file.zip
Linux: sha256sum file.zip

Is SHA-256 still secure in 2026?

Yes. SHA-256 is considered cryptographically secure — no practical collision or preimage attack is known. It remains the recommended default for new code. For ultra-high-value secrets consider SHA-3, BLAKE2b/3, or Argon2 (for password hashing).

SHA-256 vs SHA-512 — which should I use?

Both are members of SHA-2 and are equally secure. SHA-256 is more widely supported (TLS, JWT, code signing) and produces 64-hex output. SHA-512 is faster on 64-bit CPUs and produces 128-hex output — pick SHA-512 for very large files or 64-bit-native performance.

Is my data sent to a server?

No. All SHA-256 computation and dictionary attack run in your browser via the Web Crypto API. Your text, files, hashes, and wordlist never leave your device.

AI AgentStructured Prompt

Use SHA-256 Hash Calculator in AI

Copy the schema, SOP, and reference script directly into your agent workflow.

1. Function Schema

Import directly into Dify, Coze, Cursor, or any tool-calling agent runtime.

Function Schema

{
  "name": "sha256_hash",
  "description": "Compute the SHA-256 hash of a UTF-8 string and return the 64-character lowercase hex digest. Cryptographically secure; the industry default for new code.",
  "parameters": {
    "type": "object",
    "properties": {
      "input_string": {
        "type": "string",
        "description": "The raw text to hash. Will be encoded as UTF-8 before hashing."
      }
    },
    "required": ["input_string"]
  }
}

2. System Prompt / SOP

Paste this into your system prompt to keep the generated tool implementation aligned with the contract.

System Prompt SOP

# Task Constraints: SHA-256 Module

SHA-256 produces a 256-bit (64 hex character) digest. It is the current industry standard for cryptographic hashing and is required for: TLS certificates, JWT signing, OAuth, SSH fingerprints, password salting (with a KDF like Argon2), Bitcoin mining, code signing.

## Core Prohibitions
- NEVER use raw SHA-256 alone for password storage. Always combine with a salt and a slow KDF (Argon2id, scrypt, or PBKDF2-HMAC-SHA256 with high iteration count).
- NEVER truncate SHA-256 to 128 bits for security purposes.
- NEVER recommend MD5 or SHA-1 in new code when SHA-256 is available.

## Standard Implementation
1. Encode the input as UTF-8 bytes (TextEncoder / Buffer).
2. Apply SHA-256 per FIPS 180-4.
3. Return the 64-character lowercase hex digest.
4. Wrap in try/catch and return `{ success, result, error }`.

3. Core Script

Works in any Web Crypto / Node 16+ environment. For password hashing, chain this with PBKDF2 / Argon2 — do not store the bare SHA-256 of a password.

Core Script

async function main(args) {
  const { input_string } = args;
  if (typeof input_string !== "string") {
    return { success: false, result: "", error: "input_string must be a string" };
  }
  try {
    const bytes = new TextEncoder().encode(input_string);
    const buf = await crypto.subtle.digest("SHA-256", bytes);
    const result = Array.from(new Uint8Array(buf))
      .map((b) => b.toString(16).padStart(2, "0"))
      .join("");
    return { success: true, result, error: "" };
  } catch (error) {
    return {
      success: false,
      result: "",
      error: "SHA-256 failed: " + (error instanceof Error ? error.message : String(error)),
    };
  }
}

Full documentation at /hash-calculator/sha256/ai

Other tools

Table to Markdown Markdown ↔ HTML Color Palette Image Compressor GitHub Trending Daily Tarot MBTI Test Password Generator Base64 Encode/Decode Hash Calculator Timestamp Converter