Someone's sent you a PDF that needs your signature on it. Maybe a lease. Maybe a permission slip for your kid's school trip. Maybe a freelance contract you'd quite like to get countersigned before the weekend. You don't need a lecture on cryptographic signing standards. You need to get your name onto a page and send the thing back. This guide does exactly that — open the PDF in Flint, add your signature, download. Two minutes, start to finish.
Why this is genuinely easier than you think it is
For years, signing a PDF meant one of three uncomfortable paths: printing the thing out, signing it with a pen, scanning it back in, and hoping the scan didn't come out at a weird angle. Or paying for Adobe Acrobat. Or signing up for some enterprise e-signature platform that wanted to know your company's VAT number before letting you put a squiggle on a page.
None of that is necessary anymore. A modern browser can do this. Flint runs entirely in yours — no install, no account just to try it, no print-sign-scan dance. Drop the PDF in, draw or type your signature, place it where it needs to go, download. The signed copy is identical in standing to one you'd have produced with pen and scanner, with an added bonus: there's a clean audit trail recording when and where you signed, appended automatically.
The three ways to make your signature
When you click Add signature in Flint, you get a small dialog with three tabs. They all produce a signature that sits on the page the same way; the difference is purely how you like to make it. Quick tour:
Draw it (the most personal option)
Click the Draw tab and you get a blank canvas. Use a trackpad, mouse, or — if you can — your phone's touchscreen. Touchscreen wins by a mile if you have the option: the line quality is enormously better. There's a small undo button if your first attempt looks like a child's crayon sketch, which mine routinely does. Two or three goes is usually enough.
This is the option that looks most like a “real” signature — useful if the recipient is going to glance at it and you want it to feel hand-signed. If you have a stylus and a tablet to hand, even better.
Type it (the most readable option)
Click Type, type your name, pick from a handful of handwriting-style fonts. Done in five seconds. The result is neat, legible, and entirely standard-looking — half the signatures you receive in your inbox were almost certainly made this way.
Pick this option if you're self-conscious about drawing on a trackpad, if your “real” signature is an unreadable squiggle anyway, or if you just want to get the document signed and back in the next ninety seconds.
Upload a PNG (the most consistent option)
Click Upload and drop in an image of your existing signature. The format that works best is a PNG with a transparent background — your signature in black against nothing else. If all you have is a JPEG photo of your signature on white paper, that works too, but the white box will sit on the page; it looks fine on a white form and slightly odd on anything with a coloured background.
This is what people who sign a lot of documents tend to settle on. Make the signature once, save the PNG, drop it in every time. Flint also stores your signature against your account, so even without the PNG you only need to create it once.
How to add your signature to a PDF in Flint
Three clearly-bounded steps. Total time, assuming the PDF is already on your computer: under a minute.
Open Sign PDF and drop your file in
Make your signature (one of three ways)
- Draw — sketch with your trackpad, mouse, or touchscreen. Touchscreen is by far the best of the three inputs if you have it.
- Type — write your name, pick a handwriting font. Fastest option, and surprisingly tidy.
- Upload — drop in a transparent PNG of your existing signature. Best long-term option if you sign often.
Drag it onto the page, then download
What if the other party needs to sign too?
If a contract goes both ways — you sign, then the other party signs, or vice versa — Flint handles that without you needing to email the PDF back and forth manually.
Switch to Request signatures in the same tool. Drag a signature box onto the page for each person who needs to sign. Type their email next to each box. Hit Send. Each recipient receives a unique link, opens it in their browser, signs the same way you did. When everyone's done, you all get a copy of the fully-signed PDF — with the audit trail appended showing who signed when, from which IP.
It's genuinely much nicer than the sign-scan-email-repeat dance. If you'd like the deeper version, our guide on using Flint instead of DocuSign walks through the multi-party flow in detail.
After signing — small things worth doing
Once the signature is on the page and the file is downloaded, you're technically done. A few small extras tend to be worth ninety seconds each:
- Big file? Shrink it first. Signed contracts with embedded scans can balloon to 30 or 40 MB and bounce off email size limits. Compress PDF typically drops them under 10 MB without anything visibly changing.
- Add a password if it's sensitive. Password Protect PDF encrypts the file so it can only be opened by someone who knows the password — handy for contracts, medical forms, or anything containing personal information.
- Combine related files. Got the signed contract plus a separate signed addendum? Merge PDF stitches them into one tidy file in any order.
- Need to make a final edit before signing next time? Edit PDF lets you adjust the text on the page directly — useful for filling in a date field someone forgot to make fillable.
Other ways to sign a PDF (and when they make sense)
Flint isn't the only option, and the right tool partly depends on which device you're sitting at. Quick honest tour.
Preview on a Mac
Open the PDF, click the Markup icon, click the signature tool, draw with your trackpad. Free, built in, fine for casual personal use. The gaps: no audit trail, no way to send a request to someone else, and Mac-only — useless if you're on a Windows machine or a phone.
Adobe Acrobat Reader
The free Reader has a Fill & Sign feature that works well enough. The catch: you need to install it, it's heavy, and the experience pushes you towards a paid Acrobat subscription pretty aggressively. Acceptable if you already have it open.
Print, sign, scan
The traditional path. Still works. Still takes ten minutes, produces a worse-looking result, and requires a printer and scanner — neither of which most people have at home anymore. Save this for the rare document a recipient specifically insists on a pen-signed version of, which is becoming vanishingly rare.
Flint
Browser-based, no install, works on any device. Free to sign in the editor; downloading and sending signature requests need a Flint Pro plan. The audit trail is the bonus you don't get from Preview or a print-and-scan job — useful if the document is anything more than a school permission slip.
Small tips for a tidy result
- Sign on your phone if you can. Drawn signatures from a touchscreen look noticeably better than trackpad-drawn ones. Open the PDF in Flint on your phone, sign with your finger, the file syncs back into your account.
- Make a transparent PNG once, reuse forever. If you sign things regularly, take ten minutes to produce a clean transparent PNG of your signature once. Drop it into Flint, save it to your account, never think about it again.
- Resize, don't overlap. If the signature line on the form is small, shrink the signature box to match. A massive signature drooping below the line looks unpolished. Drag a corner of the box to scale it.
- Add the date in a separate field. Most contracts ask for a signature and a date. Use Flint's date field tool to drop today's date in next to your signature rather than scrawling it into the signature itself.
- Convert Word documents first if needed. If the original is a
.docx, run it through Word to PDF before signing. Signing a PDF version preserves layout in a way signing a Word file never quite manages.
Adding a signature to a PDF: frequently asked questions
Do I need an account to sign a PDF?
Not to try it. You can open a PDF and place a signature on it without signing up. To download the signed result or send a signature request to someone else, you'll need a Flint Pro subscription.
Is the signature I add legally valid?
For everyday commercial documents — contracts, NDAs, offer letters, permission slips, supplier agreements — yes. Signatures applied in Flint qualify as electronic signatures under the ESIGN Act, UETA, eIDAS, and the UK Electronic Communications Act. For a deeper take on the legal side, see our electronic signatures guide.
What if I make my signature wrong?
Click your existing signature in the toolbar and there's a small “Edit” option that lets you redraw, retype, or re-upload. The placed signature on the page updates automatically. You can also just delete the placed signature and drop a fresh one on.
Can I sign on my phone?
Yes. Flint works in mobile Safari and Chrome on Android. Drawn signatures from a touchscreen actually come out cleaner than ones drawn with a mouse, so phones are often the better device for this.
Does Flint keep my signed documents private?
Yes. Signed PDFs sit in your private Flint library. We don't share, sell, or train on your documents. You can delete them anytime.
What about handwriting that fills a multi-line signature box?
The drawn signature mode lets you make a signature as small or large as you want; the placed box is then resizable on the page. If a form has a giant signature box (some legal forms do), you can scale the signature to fill it, or just centre a normal-sized signature inside.
Can I add initials in addition to a full signature?
Yes — the toolbar has a separate initials field that uses a shorter version of your signature, useful for the per-page initialling some contracts require.
What file types can I sign?
PDFs directly. For Word documents (.docx), OpenDocument (.odt), or rich text (.rtf) files, run them through Word to PDF first — takes a couple of seconds.
Ready to sign yours?
Open Flint's Sign PDF tool, drop your file in, and you'll have a signed copy in your downloads folder before the kettle boils. If you need the recipient to counter-sign too, switch to Request signatures and let Flint handle the back-and-forth for you.