How to Work With Files Without Uploading Them Anywhere
Every tool linked from these pages does its work inside your browser. The file you choose is read by the page already in front of you, processed on your own machine, and handed back as a download. It is not transmitted, so there is no copy on a server to be retained, logged, indexed or handed to anyone, and no terms of service governing what happens to it next. You do not have to take that on trust: open your browser's network panel and watch while a file is processed, or disconnect from the network entirely and use the tool anyway. Each page below covers one job and the specific exposure of the specific file it operates on, because a contract, a photograph, a session token and a .env file leak completely different things.
Every page here embeds the Hash Generator. The file hasher is on every page here because it takes any file at all and proves the point: disconnect from the network, drop a file in, and it still returns a checksum you can compare against a published one.
36 pages in this section.
File type PDF documents
Merge PDF files without uploading them
Combine PDFs on your own machine. What merging does to the metadata of every source document, and how to check nothing was sent.
Split a PDF without uploading it
Pull pages out of a PDF on your own machine. Why a single extracted page still carries the whole document's properties with it.
Compress a PDF without uploading it
Shrink an image-heavy PDF in your browser. What compression actually removes, and why a text-only document barely changes size.
Rotate PDF pages without uploading the file
Turn pages 90, 180 or 270 degrees in your browser. Why rotation is a page property, what it fixes on a scan and what it cannot fix.
Sign a PDF in your browser without uploading it
Draw, type or place a signature on a PDF locally. Why a visual signature is not a cryptographic one, and when that difference matters.
Add a watermark to a PDF without uploading it
Stamp text or an image across PDF pages in your browser. Why a watermark deters copying but never hides what sits underneath it.
Add page numbers to a PDF without uploading it
Stamp page numbers locally with position, format and a starting number. Why the stamped number and the printed number often disagree.
Edit PDF metadata without uploading the document
Read and rewrite title, author, subject, keywords, creator, producer and creation date in your browser, before the file goes anywhere.
Extract text from a PDF without uploading it
Pull the text out of a PDF in your browser. Why extraction finds nothing in a scan, and why it never removes the document's metadata.
Convert PDF pages to images without uploading
Turn PDF pages into images in your browser. Rasterising drops the text layer, which removes hidden text and removes searchability too.
Combine images into a PDF without uploading them
Build a PDF from photos or screenshots in your browser. Why phone photos need their EXIF checked before they go into a document.
Convert a Word document to PDF without uploading it
Turn a .docx into a PDF in your browser. What a .docx stores about its authors, and what to check on the PDF before you send it.
Turn HTML into a PDF without uploading your markup
Render HTML to PDF in your browser. Your markup is not uploaded, though remote images and fonts it references are still fetched normally.
File type Images and photos
Compress images without uploading them
Shrink pictures in your browser with five presets. What each preset does, and the two formats the compressor will not accept at all.
Resize images without uploading them
Resize to exact pixels, a percentage or a preset in your browser. The 8192 pixel and 32 megapixel ceilings, and what to check afterwards.
Crop an image without uploading it
Crop to a free or fixed ratio in your browser, with rotation and flips. Why cropping genuinely removes pixels but never removes EXIF.
Convert between image formats without uploading
Convert to JPEG, PNG, WebP, BMP or AVIF in your browser. What each format is for, and why a GIF converts as its first frame only.
Remove EXIF data from a photo without uploading it
View and strip EXIF in your browser. What a phone photo records: coordinates, the exact timestamp, the camera model and its serial number.
Convert SVG to PNG without uploading the file
Rasterise an SVG to PNG, JPEG or WebP in your browser. Why an SVG is a text file that usually carries layer names and editor metadata.
Optimise an SVG without uploading it
Clean up SVG markup in your browser. What an exported SVG carries beyond the drawing, and why that is a disclosure risk, not just weight.
Watermark a photo without uploading the original
Add a text or image watermark to a photo in your browser. Why a watermarked photo still carries all the EXIF it started with.
File type Data, config and code files
Format and validate JSON without uploading it
Tidy and check JSON in your browser. The JSON people paste into a formatter is usually a live API response full of real records.
Open and filter a CSV without uploading it
Sort, filter and hide columns across up to 100,000 rows locally. A customer export is personal data, and opening it should not be a transfer.
Convert CSV to JSON without uploading the file
Convert between CSV and JSON in your browser. The traps that silently change data: leading zeros, dates, delimiters, empty versus null.
Convert YAML to JSON without uploading the file
Convert YAML and JSON both ways in your browser. Infrastructure YAML is configuration, and configuration is where credentials sit.
Convert XML to JSON without uploading the document
Convert XML in your browser. Why attributes, namespaces and repeated elements have no single correct JSON equivalent to fall back on.
Compare two files without uploading either of them
Diff two versions of a document or a config in your browser. A hosted comparison receives both files, which doubles the exposure.
View a file as a hex dump without uploading it
Inspect any file's raw bytes in your browser. If you cannot identify a file, uploading it to find out is the wrong first move.
Minify JavaScript without uploading your source
Minify scripts and stylesheets in your browser. Source carries comments, endpoints and internal names, and minifying is not obfuscation.
File type Credentials, hashes and codes
Hash a file without uploading it
Checksum a file in your browser with SHA-256 and eight other algorithms. A hash proves the bytes match; it keeps nothing secret.
Decode a JWT without sending it to a website
Read and verify a token in your browser. A JWT is a live credential: pasting one into a hosted decoder hands over a working session.
Check a .env file without uploading your secrets
Find duplicate keys, mask values and generate a .env.example locally. A .env is nothing but credentials, so uploading one means rotating them.
Base64 encode a file without uploading it
Encode files or text in your browser, with a URL-safe variant and line wrapping. Base64 is a transport encoding, never encryption.
Encrypt text in your browser without uploading it
AES encryption that runs locally, so the plaintext and the passphrase both stay put. What that protects, and what it cannot protect.
Generate a password without a server seeing it
Create passwords in your browser. A password produced by a remote service is a password that existed on somebody else's machine first.
Generate a QR code without uploading what it encodes
Make a QR code in your browser. The payload never leaves, and the result points where you said rather than through somebody else.