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Sign a PDF
Stamp a seal onto a PDF: upload the document (up to 20 MB), drag the seal image to the spot you want on any page, or tick the edge seal to stamp along the right edge of every page. An encryption certificate (PKCS12) can be uploaded or generated online to add a digital signature that Adobe Reader verifies. Sealing happens in one pass inside server memory — the file, seal and certificate are never written to disk and are destroyed right after signing. Draw a transparent seal PNG with the electronic seal maker first for the best result.
No sign-up. The PDF is sent to our backend, stamped, edge-sealed and digitally signed in server memory, then returned; the file, seal and certificate are never written to disk.
More tools in More tools
- SQL formatter — Paste SQL to get clause-aware line breaks, indentation and upper-cased keywords in real time, with one-click minify, copy and download as a .sql file.
- Nginx formatter — Paste nginx.conf to re-indent it by brace level; directives, comments and quoted strings are preserved exactly and unbalanced braces are reported.
- URL encoder / decoder — Switch between encoding and decoding with either encodeURIComponent or encodeURI scope, showing the encoded character count live.
- Regex tester — Enter a regular expression and test text to highlight every match live, list each match position and its capture groups, and preview the replacement result.
- Markdown editor — Edit Markdown on the left and preview it live on the right, with a toolbar that inserts headings, lists, tables and code blocks in one click; images and files can be uploaded, dropped or pasted in as embedded content, Markdown / Word / PPT / PDF / Excel / EPUB / RTF / OpenDocument documents convert to Markdown locally in your browser, and the rendered HTML is ready to copy or export as PDF.
- Password generator — Generate strong random passwords from a length and character set, optionally excluding look-alike characters, in batches, with a strength and entropy estimate.
- Amount in words — Convert an amount into Chinese financial capital characters (yuan, jiao, fen) along with the upper-case digits, the Chinese reading and a thousands-separated form.
- IP address — Parse an IPv4 / IPv6 address into its type, binary and decimal forms and subnet details (network address, broadcast address, usable range). Opening the page also looks up your public outbound IP from our backend, configured per environment.
- Web-safe colours — Browse all 216 web-safe colours grouped by the red channel (each channel steps 00 / 33 / 66 / 99 / CC / FF); click a swatch to select it, then copy the HEX, the 3-digit shorthand, RGB, HSL, HSV, CMYK and the contrast against black or white text. Any colour you type is snapped to the nearest safe colour, and you can filter by value or show greys only.
- Cron expression parser — Paste a cron expression to see it in plain words with upcoming run times, or build it field by field; crontab and Quartz both work.
- Emoji library — Browse all 1849 emoji from Unicode 15.1 in nine groups (smileys, people, animals, food and more). Search by Chinese or English name — everyday words like "red packet" or "happy birthday" work too — then click any emoji to copy it instantly; recent picks are remembered for next time. Everything runs locally in the browser; nothing is uploaded.
- Properties to YAML — Paste Java .properties content and get a nested YAML that follows the dot hierarchy: equals, colon and whitespace separators are all supported, along with \t \n \uXXXX escapes and line continuations that end with a backslash. Every value is emitted as a string (single-quoted; multi-line content keeps its line breaks as a block scalar), comments and blank lines follow the entry they belong to, and keys that collide with nested children are flattened back to their full dotted names with a note at the end. Everything runs locally in the browser; nothing is uploaded.
- YAML to Properties — Paste YAML content and get flattened .properties key-value pairs: nesting and arrays expand along the dot hierarchy (arrays use index keys), every value is emitted as a string and escaped the java.util.Properties way; whole-line and end-of-line comments move above the entry they belong to (in .properties a # only works at the start of a line — one appended after a value would be read into it), and the result can be re-sorted in ascending / descending order. Everything runs locally in the browser; nothing is uploaded.
- YAML validator — Paste YAML and check the syntax as you type: when it is invalid, the page points at the exact line and column, shows the offending line with a ^ marker and gives a concrete fix suggestion (unclosed quotes, unbalanced brackets, misaligned indentation, duplicate keys, tab indentation, full-width colons and more); when it is valid, it reports the document, line and character counts plus warnings about legal-but-risky writing. Everything runs locally in the browser; nothing is uploaded.
- Electronic seal maker — Draw an electronic seal locally and export it as a transparent PNG. Company seals take a name and code, a seal type (official / contract / finance / invoice, or custom), a circle or ellipse shape, an optional centre star and any text colour; the name and type text scale automatically with the character count. Personal seals come as a square four-character grid or a circle, in relief or intaglio carving and Song / Kai / Hei fonts. Everything is drawn in the browser; nothing is uploaded.
Frequently asked questions about Sign a PDF
- Does the content these tools process stay local?
- No. Your input exists only in the memory of the current page, is released when you reload or close it, and is never written to local storage.
- Can I keep using the tools offline?
- Once the page has loaded, formatting, encoding, regex and password calculations need no network; only the IP address page needs to be online, because it asks our backend for your local outbound address when it opens.
- Do I need to register or pay to use Sign a PDF?
- Almost every tool is free, needs no registration or sign-in and has no usage limit; the few pay-per-use features (such as AI watermark removal, AI image generation, AI upscaling, AI annotation, and AI flowchart, mind-map and Mermaid generation) state their prices on the page.
- Is the data I process with Sign a PDF uploaded to a server?
- No. Calculation and rendering run locally in the browser and your input is never sent to a server; only the IP address page asks our backend for your outbound address when it opens, and that request carries none of your input. Features that need the backend (such as AI watermark removal, AI image generation, AI upscaling, AI annotation, AI flowchart and mind-map generation and "Financial statements – Small Business Accounting Standards") state their upload scope on their own pages.
About Local Toolbox
Local Toolbox gathers the small tools you reach for every day into one place: formatters, encoding converters, date maths, ID card and address parsing, image and QR code handling, password and amount conversion. Open a page and start working — no sign-up, and almost every tool has no usage limit.
Most features compute inside your browser, so your input never leaves your device; the pages are plain static assets, load fast and keep working offline. The IP page asks our backend for your outbound address when it opens and sends none of your input. AI watermark removal, AI background removal, AI image generation and AI upscaling send content to our backend for inference (watermark removal is ¥1 per run; background removal is ¥1 per run; image generation and upscaling are priced by resolution — 2K ¥2, 4K ¥3); AI annotation sends images to a large model that locates the target and returns coordinates (¥0.5 per image, refunded only when every image in the batch fails); AI flowchart, AI mind-map and AI Mermaid chart generation send your text description to a model that builds the diagram (three separate products, charged ¥0.5, ¥0.5 and ¥0.5 per run respectively); and the accounting helper sends the income, expense, social-insurance and balance figures you fill in to generate a report (¥0.5 for the spoken analysis, ¥1 for the report). These features accept Alipay only, upload nothing before payment succeeds, and refund automatically if processing fails.
- Local first: Parsing, conversion, encoding and image processing all happen in your browser and nothing you type is uploaded (AI watermark removal and AI background removal need the image, AI image generation and upscaling need one upload to obtain a URL, AI annotation needs the images for the model, AI résumé rewriting needs your résumé text, AI flowchart and mind-map generation need your text description, and the accounting helper needs the figures you submit).
- Pay per use, prices in plain sight: Almost every tool is free, needs no account and has no usage limit. Only AI watermark removal (¥1 per run), AI background removal (¥1 per run), AI image generation and AI upscaling (2K ¥2, 4K ¥3), AI annotation (¥0.5 per image), AI résumé rewriting (¥0.5 per run), AI flowchart, mind-map and Mermaid chart generation (¥0.5, ¥0.5 and ¥0.5 per run) and the accounting helper (¥0.5 for the spoken analysis, ¥1 for the report) are charged per use. Payment is Alipay only, nothing is uploaded before you pay, and failed runs are refunded automatically.
- One link per tool: Every tool has its own link, so bookmarks and shared URLs always land on the same page.
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