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SHA-256 Hash Calculator — Bitcoin & HTTPS Standard Hash

Global industry standard powering Bitcoin and HTTPS certificates. 256-bit output with 128-bit security. The most trusted SHA-2 variant.

Features

  • ✓Compute SHA-256 hashes online — the global industry standard powering Bitcoin and HTTPS
  • ✓Real-time 256-bit hash computation with 64 hex character output, Web Crypto API accelerated
  • ✓One-click copy, save as .txt, and uppercase/lowercase toggle
  • ✓Used in blockchain mining, SSL/TLS certificates, and digital signatures worldwide
  • ✓Hash verification against known SHA-256 checksums with auto-detect
  • ✓100% browser-based — zero server uploads, hardware-accelerated hashing
  • ✓Hash comparison — paste an expected 64-character SHA-256 hash for instant match/mismatch verification
  • ✓Real-time input length counter — displays character and byte counts alongside the hash
  • ✓Cross-platform browser access — compute SHA-256 hashes on any device without installing software
  • ✓Session history — retains previous SHA-256 results during the session for easy reference and comparison

How to Use

  1. 1Type or paste your text into the input box above.
  2. 2Your hash digest appears instantly — no page reload needed.
  3. 3Toggle UPPERCASE / lowercase to change the hex output format.
  4. 4Click the copy icon to copy the hash to clipboard, or use Save to save as .txt.
  5. 5Paste an expected hash into the Verify field to check for a match.
  6. 6How to verify a software download with SHA-256: obtain the publisher's SHA-256 checksum from their official website, paste it into the Verify field, then compute the hash of your downloaded file content. A green checkmark confirms the file is authentic.
  7. 7How to check a Bitcoin transaction hash: paste the raw transaction hex into the input and compute its double SHA-256. The first hash is used as the transaction ID in Bitcoin's blockchain.
  8. 8How to generate a strong password hash: combine a password with a unique salt, hash the combination with SHA-256, and store the result. For production use, prefer bcrypt or Argon2id, but SHA-256 is useful for custom authentication systems when combined with salt and iteration.
  9. 9How to create a content integrity proof for APIs: compute SHA-256 of the API response body and include it in the response headers. Clients can recompute and verify that the response was not tampered with during transit.
  10. 10How to deduplicate data using SHA-256: compute SHA-256 of each data record or file. Store the hash as a unique key. Identical records produce identical hashes, enabling efficient duplicate detection.

Frequently Asked Questions

What is SHA-256?

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SHA-256 is the most widely used member of the SHA-2 family, producing a 256-bit (64 hex) hash. Published by NIST in 2001, it is the cryptographic backbone of the modern internet, used in HTTPS certificates, Bitcoin mining, digital signatures, and password hashing systems.

How does Bitcoin use SHA-256?

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Bitcoin uses SHA-256 in two critical ways: (1) Proof-of-work mining requires miners to repeatedly hash block headers until finding a hash below the target difficulty. (2) Bitcoin addresses are generated by applying SHA-256 followed by RIPEMD-160 to public keys.

Can SHA-256 be reversed or cracked?

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No. SHA-256 has 128 bits of security against collisions. There are no known practical attacks. Even with all of Bitcoin's mining power (~400 exahashes/second), finding a SHA-256 collision would take billions of years.

SHA-256 vs SHA-512: which is faster?

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On 64-bit processors, SHA-512 is actually faster than SHA-256 because it processes 64-bit words instead of 32-bit words, making better use of modern CPU architecture. However, SHA-256 produces shorter 64-char hashes vs SHA-512's 128 chars.

Is SHA-256 suitable for password hashing?

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SHA-256 alone is not ideal — it is designed to be fast, which is the opposite of what password hashing needs. For password storage, always use bcrypt, Argon2id, or scrypt. If you must use SHA-256 in a password context, use PBKDF2 with a high iteration count.

How long is a SHA-256 hash output?

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SHA-256 produces a 256-bit (32-byte) hash displayed as 64 hexadecimal characters. Each pair of hex characters represents one byte of the hash.

What is SHA-256 used for besides Bitcoin?

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SHA-256 is ubiquitous: TLS/SSL certificates, SSH key fingerprints, PGP/GPG signatures, Docker image verification, Debian/Ubuntu package checksums, IPFS content addressing, and nearly every modern cryptographic protocol.

Is SHA-256 resistant to quantum attacks?

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SHA-256 provides 128-bit security against classical attacks. Grover's algorithm would reduce this to 64-bit effective security on a quantum computer. For quantum-resistant applications, use hash sizes of 384 bits or larger.

Can two files have the same SHA-256 hash?

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Theoretically yes (collisions exist for any hash function), but finding one requires approximately 2^128 operations — computationally infeasible with any known or foreseeable technology. No SHA-256 collision has ever been found.

What is the difference between SHA-256 and HMAC-SHA-256?

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SHA-256 is a plain hash function. HMAC-SHA-256 is a keyed construction that combines a secret key with the message using SHA-256, providing authentication in addition to integrity verification.

How does SHA-256's algorithm work?

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SHA-256 processes input in 512-bit blocks through 64 rounds of compression functions. It uses 32-bit words with logical operations (AND, OR, XOR, rotations) and modular additions. The internal state is 256 bits divided into eight 32-bit words.

Why is SHA-256 considered the standard?

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SHA-256 strikes an optimal balance of security (128-bit collision resistance), output size (64 char), and performance. It's standardized by NIST, supported in hardware by all major CPU manufacturers, and required by nearly all security standards and regulations.

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