Double SHA-256 Hash Generator
Generate a double SHA-256 (SHA-256d) hash of any text or raw hex bytes, as used by Bitcoin, in hexadecimal or base64, and optionally verify it against an expected hash.
Input
Choose Hex bytes to hash raw binary data, e.g. a Bitcoin block header.
Hex comparison is case-insensitive; base64 is case-sensitive.
Output
Only shown when an expected hash is provided.
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/double-sha256-hash-generator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"inputText": "",
"inputMode": "text",
"outputFormat": "hex",
"expectedHash": ""
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `double-sha256-hash-generator` tool (Double SHA-256 Hash Generator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
Embed widget
<iframe
src="https://iotools.cloud/embed/double-sha256-hash-generator/"
width="100%" height="520" frameborder="0" scrolling="no" loading="lazy"
title="Double SHA-256 Hash Generator — iotools.cloud"
sandbox="allow-scripts allow-forms allow-same-origin allow-downloads allow-popups allow-popups-to-escape-sandbox"
allow="clipboard-write"
style="width:100%;border:1px solid #e5e7eb;border-radius:12px;overflow:hidden"></iframe>
<script src="https://iotools.cloud/embed.js" async></script>Drop this into your own page — free, no key required, just a link back.
| Cost per API/MCP call | From 5 credits |
|---|---|
| Need more credits? | View pricing |
Also available with
Guides
Generate a double SHA-256 (SHA-256d) hash of any text, right in your browser. Pick hexadecimal or base64, switch the input to raw hex bytes, and optionally paste an expected hash to verify it. Nothing you type leaves your device.
What is double SHA-256?
Double SHA-256 runs SHA-256 twice: the first digest is hashed again to produce the final 256-bit value. Bitcoin uses it for block hashes, transaction IDs and checksums, because hashing twice protects against length-extension attacks on plain SHA-256.
How to use
- Enter your message, or choose Hex bytes and paste raw binary data as hex.
- Choose hex (lower/upper) or base64 output.
- Copy the result, or paste an expected hash to check for a match.
Is it the same as SHA-256?
No. A plain SHA-256 digest differs from SHA-256d of the same input. Bitcoin displays block and transaction hashes byte-reversed; reverse the hex bytes if you are comparing against a block explorer.