A private file & data workbench
Compress an image, verify a download's checksum, encrypt a note, convert JSON to CSV. Every tool below runs entirely inside your browser tab — the file you open is never sent to a server, because there is no server to send it to.
// the workbench
Twelve tools
Image Compressor & Converter
Compress, resize and convert JPEG, PNG and WebP images. Batch-friendly, with a live before/after size readout.
FilesFile Checksum Calculator
Verify a download's SHA-256, SHA-1, MD5 or CRC32 checksum against the value the publisher listed.
FilesImage to Base64
Encode an image to a Base64 data URI you can paste straight into HTML or CSS.
FilesAES-256 Text Encryption
Encrypt and decrypt text with password-based AES-256-GCM, using the browser's own Web Crypto implementation.
CryptoHash Generator
Generate SHA-256, SHA-1, SHA-384 and SHA-512 hashes from any text input.
CryptoHMAC Generator & Verifier
Compute and verify HMAC-SHA256 and other HMAC signatures — useful for checking webhook payloads.
CryptoPassword Generator
Generate strong random passwords and passphrases from the browser's cryptographic RNG.
CryptoJSON ↔ CSV Converter
Convert a JSON array to CSV and CSV back to JSON, with nested-key flattening.
DataText Diff Checker
Compare two blocks of text and highlight what changed, line by line.
DataTest Data Generator
Generate realistic mock records — names, emails, addresses — as CSV or JSON for testing.
DataBase64 Encoder / Decoder
Encode and decode Base64 text, including UTF-8 and URL-safe variants.
DataUUID Generator
Generate random version-4 UUIDs, one at a time or thousands in bulk.
DataHow we can promise nothing is uploaded
"Private" is easy to claim and easy to check. Three ways to verify it yourself, in under a minute:
- Watch the network. Open your browser's developer tools, switch to the Network tab, then run any tool with a real file. You will see requests for the page, its stylesheet and its script — and none carrying your file or your text.
- Pull the plug. Load a tool, then turn off your Wi-Fi and use it. Every tool here keeps working offline, because all the logic already ran down to your machine.
- Read the source. Each tool is a single page of plain JavaScript with no build step and no bundler. View source and you can read the whole thing.
Under the hood the hashing, HMAC and AES tools call Web Crypto (crypto.subtle) — the same primitives your browser uses for HTTPS — rather than a hand-rolled implementation. Image work uses FileReader and <canvas>. Where randomness has to be unguessable — the password generator, UUIDs and AES salts and IVs — it comes from crypto.getRandomValues(). The test-data generator uses ordinary Math.random() to vary its mock records, which is the right tool for fake data and should not be relied on for anything secret.
One honest caveat: larely is free because it shows ads, and our ad provider sets its own cookies and sees your IP address, as it would on any site. So the promise here is specifically about your data — files and text you load into a tool genuinely never leave your device — and not a claim that the page is free of all third-party tracking. The privacy policy spells out exactly what the ad provider collects.
Guides
Reference notes for the things these tools do — each one paired with the tool it explains.
Looking for a calculator?
larely started as a general collection of 251 calculators and converters. Those all still work and are still free — they now live in the full tool archive. This front page is deliberately just the workbench.