Security Tools
Every security tool you need — private, in your browser
Generate passwords and IDs, encode and hash data, decode JWTs and certificates, and encrypt with AES or PGP. 39 free tools that never upload your data — no signup, no limits.
All security tools
Popular security tools
- Password GeneratorCreate strong random passwords or passphrases with a live strength meter.
- UUID GeneratorGenerate UUID v4, v7 or nil identifiers in bulk, and check any UUID.
- Base64 EncodeTurn text or any file into Base64, with URL-safe, padding and line-break options.
- Hash GeneratorGet MD5, SHA-1, SHA-2, SHA-3 and CRC-32 of text or a file, with HMAC and checksum compare.
- URL Encode / DecodePercent-encode or decode text and URLs, with component, full-URL and form modes.
Generators
5 toolsPassword Generator
Create strong random passwords or passphrases with a live strength meter.
UUID Generator
Generate UUID v4, v7 or nil identifiers in bulk, and check any UUID.
Secret Key Generator
Generate random secret keys, API keys and tokens in hex, Base64, Base32 or your own alphabet.
ULID Generator
Generate time-sortable ULIDs, decode any ULID to its timestamp, and create IDs for a chosen date.
NanoID Generator
Generate NanoID-style random IDs with your own length and alphabet, and estimate collision risk.
Encode & Decode
7 toolsBase64 Encode
Turn text or any file into Base64, with URL-safe, padding and line-break options.
Base64 Decode
Decode standard or URL-safe Base64 to text and find exactly where bad input breaks.
Image to Base64
Convert a PNG, JPG, SVG or other image into a data URI, an HTML img tag or CSS.
Base64 to Image
Paste Base64 or a data URI to preview the picture and download it with the right extension.
URL Encode / Decode
Percent-encode or decode text and URLs, with component, full-URL and form modes.
Base32 Encode / Decode
Convert text and files to Base32 and back, with RFC 4648, extended hex and Crockford alphabets.
Base58 Encode / Decode
Encode and decode Base58 with Bitcoin, Flickr and Ripple alphabets, plus Base58Check checksums.
Hash & Checksum
8 toolsHash Generator
Get MD5, SHA-1, SHA-2, SHA-3 and CRC-32 of text or a file, with HMAC and checksum compare.
MD5 Hash Generator
Get the MD5 hash of text or a file in your browser, with a copy button and checksum compare.
SHA-1 Hash Generator
Calculate the SHA-1 hash of text or a file in your browser and compare it with a published value.
SHA-256 Hash Generator
Generate the SHA-256 hash of text or a file in your browser and verify it against a known checksum.
SHA-512 Hash Generator
Generate a SHA-512 hash of text or a file in your browser and compare it with an expected value.
CRC32 Checksum
Calculate the CRC-32 checksum of text or a file as hex and decimal, right in your browser.
Checksum Calculator
Verify a downloaded file against the publisher’s checksum with SHA-256, MD5, SHA-1 or CRC-32.
HMAC Generator
Calculate an HMAC of text or a file with a secret key, and check a webhook signature.
Encryption & Keys
4 toolsAES Encrypt
Encrypt text or files with AES-256-GCM using just a password, entirely in your browser.
AES Decrypt
Decrypt AES-GCM, CBC or CTR text and files with a password, or with a key and IV.
Key Pair Generator
Generate RSA, ECDSA or Ed25519 key pairs in PEM, JWK and OpenSSH format, entirely in your browser.
Digital Signature
Sign a message or file with a private key, or check a signature with a public key, in your browser.
Tokens & Certificates
3 toolsJWT Decoder
Decode a JSON Web Token, edit its claims, re-sign it and check its signature, all in your browser.
TOTP Generator
Generate and check time-based one-time codes for testing two-factor login.
Certificate Decoder
Paste a PEM certificate or CSR and read its subject, dates, SANs, key and fingerprints.
Password Security
2 toolsPGP
3 toolsPGP Key Generator
Create an OpenPGP key pair in your browser: Curve25519 or RSA, with an optional passphrase and expiry.
PGP Encrypt
Encrypt text to one or more PGP public keys, or with just a passphrase, and optionally sign it.
PGP Decrypt
Decrypt a PGP message with your private key and passphrase, and check who signed it.
Post-Quantum
2 toolsClassic Ciphers
5 toolsCaesar Cipher
Shift letters by any amount to encrypt or decrypt, or try all 25 shifts at once.
ROT13
Rotate letters by 13, digits by 5 or all printable characters by 47, in one click.
Morse Code
Translate text to Morse and back, then play it as beeps or download a WAV file.
Vigenère Cipher
Encrypt and decrypt with a keyword, see the key stream and try the autokey variant.
Atbash Cipher
Mirror the alphabet so A becomes Z and B becomes Y, in Latin, Greek or Hebrew.
39 tools shown
Workflows
Common jobs, done in a few steps
Create secure credentials
Generate a strong password, a unique ID, then fingerprint a value.
Work with encoded data
Decode a Base64 string, fix a URL-encoded value, then encode it again.
Embed an image in code
Turn an image into a data link, and back again to check it.
Generate a unique key
Make a secret key, then check its hash or sign something with it.
Why Nelstack
Fast, private security tools
Your data never leaves your device
Passwords, keys, tokens, files and images are processed in your browser — nothing is uploaded or stored.
Cryptographically secure randomness
Passwords, UUIDs and random picks use the browser’s secure random generator, not Math.random.
Files as well as text
Hash a download, encode an image or read a certificate file — files are read locally.
No caps or signup
No daily quota, no account and no ads inside the tools.
Works offline once loaded
After the page loads, processing needs no connection.
Built for phones too
Touch-friendly controls that fit a small screen.
Working with images or text?
These live in their own tool areas and work the same private, in-browser way.
Security Tools FAQ
Are these security tools really free?
Yes. Every tool is free with no signup, no daily limit and no watermark. You can generate or convert as much as your browser can handle.
Is my data sent to a server?
No. Every Security Tool runs entirely in your browser. Passwords, keys, tokens, files and text are processed on your device and are never uploaded or stored, which matters for credentials and private files.
Are the generated passwords and UUIDs secure?
Passwords, UUIDs and random picks come from your browser’s cryptographically secure random number generator (crypto.getRandomValues), not from Math.random.
Do the tools work offline?
Once a tool page has loaded, the processing needs no network connection, so you can keep generating, encoding and hashing if your connection drops.
Can I use files instead of pasting text?
Yes. Hashing, encryption, Base64 and image tools accept files that are read locally in your browser; nothing is uploaded. Very large files depend on your device’s memory.
Where are the QR code reader, random number generator and image tools?
The QR code reader, random number generator and random name picker are in Utilities. Image conversion and editing live in Image Tools, which links to Image to Base64 and Base64 to Image here.