Security

Show each HMAC step of HKDF Extract+Expand for protocol key derivation, including PRK, T(n), and OKM.

Cryptography

Hash the same input with MD5, SHA-1, SHA-256, SHA-512, BLAKE2b, and BLAKE3 at the same time and compare them side by side: output length, hex/Base64 digest, security status (broken / modern), and a relative speed benchmark. Great for teaching, choosing a hashing algorithm, or sanity-checking checksums.

Security

Compute the CRC32 checksum (IEEE 802.3 polynomial) of any text or raw bytes. Output as hex, decimal or binary. Accepts plain text (UTF-8) or raw bytes via hex/base64 input.

Security

Compute an HMAC message-authentication signature over a message + shared secret using SHA-1/SHA-2/SHA-3/BLAKE2, or verify an incoming signature against the secret — with webhook presets for Stripe / Slack / GitHub and constant-time comparison

Security

Generate Argon2id password hashes with tunable memory, iterations, parallelism, salt length, and PHC output

Validation

Audit heading structure from a live URL or pasted HTML, then flag skipped levels, multiple h1 usage, style-only heading abuse, and title metadata drift

Security

Inject visible or signature-style watermark fields into CSV or JSON exports so shared datasets can be traced later

Validation

Validate International Bank Account Numbers (IBAN)

Validation

Validate phone numbers from multiple countries including China, US, and more with detailed formatting and carrier info

Validation

Validate postal codes from multiple countries including US ZIP, UK Postcode, Canada, and more

Validation

Validate JSON data against a JSON Schema to verify structure and data types

Validation

Validate International Bank Account Number (IBAN) and SWIFT/BIC codes with checksum verification