For freelancers & independent contractors

Your contracts and W-9 never leave your laptop.

Sign a client contract, fill your W-9, and redact a rate or a name — without the file ever being uploaded. AttachKit runs entirely in your browser, so your SSN and your clients' agreements are never copied to a server you don't control. And unlike a promise in a privacy policy, you can prove it.

New: tell the document what to do

The Private PDF Agent (in beta) lets you describe a change in plain English — “delete the blank last page”, “add page numbers to the contract” — and review a clear plan before anything is applied. The privacy posture is unchanged: the file never leaves your browser; only the extracted text is sent to the AI so it can locate pages, never the document itself. Nothing changes until you approve the plan, and your original is never modified.

Why "in your browser" matters when it's your name on the line

Most online PDF tools upload your file to their servers to process it. For a throwaway flyer that's fine. For a signed master services agreement, an NDA, or a W-9 with your Social Security number on it, it means a copy of sensitive material now lives on infrastructure you don't control — subject to their retention and their breaches.

AttachKit doesn't upload the file at all. The PDF is parsed, filled, signed, and redacted inside the browser tab you have open. The server never receives it — and most of the time isn't contacted at all. The privacy posture is the same as working on the file in a desktop app: nothing transmitted, no server-side copy to retain.

Don't take our word for it — check the network tab

This is the part you can verify in thirty seconds, today, before you trust us with anything:

• Open any tool (try filling your W-9).
• Open your browser's developer tools and switch to the Network tab.
• Drop in a PDF and run the tool.
• Watch the request list. Your file is never sent. The full technical account of what does and doesn't touch our server is on the security page.

The tools you actually reach for

Sign a contract — and let the client verify it

Sign or counter-sign in your browser. Every signed PDF carries a content-bound proof: change a single byte afterward and verification fails. Your client can confirm the signature — and that the contract wasn't altered after you signed — at attachkit.com/verify, and the check also runs offline. PAdES-aligned (not a QES — see the FAQ on legal validity below).

Fill your W-9 in seconds

The form every client asks for so they can 1099 you at year-end. Fill it instantly from your saved profile — name, address, SSN or EIN — then sign it on the same page. Your taxpayer ID is written into the PDF on your own device and never uploaded. Start with Fill W-9, or browse the whole form library.

Redact before you forward

Sharing a template contract with a new client? Strip the previous client's name, an old rate, or your own SSN first. Draw redactions yourself or let optional AI suggest likely PII (it sends only the extracted text, never the file), then export with forensic scrub so what's under each mark is removed from the file — not just hidden. See Redact.

Where we're honest about the limits

A tool you'd put your name on should tell you what it isn't:

• Not a Qualified Electronic Signature (QES) under eIDAS, and not on the Adobe Approved Trust List. For a counterparty that specifically requires a qualified certificate, use a QES provider.
• Not tax or legal advice. Filling a W-9 or signing a contract with AttachKit creates no professional relationship. Check the current IRS instructions or a professional for your situation.
• Optional AI sends field text, never the file. Auto-fill and PII suggestions are opt-in and clearly labeled; they transmit only extracted text to the AI provider. Skip them and nothing leaves your browser at all — and Local AI mode keeps even that on your device.

Frequently asked

I have to put my SSN on a W-9 — does that get uploaded anywhere?

No. AttachKit fills the W-9 inside your browser tab from your saved profile — your name, address, and SSN or EIN are written into the PDF on your own device, and the file is never sent to our server. You can prove it: open your browser's developer tools, switch to the Network tab, and fill the form — you'll see no upload. Then sign it on the same page and send the finished PDF to your client yourself.

Can a client actually verify a signature I add, or is it just a picture?

Every PDF you sign carries a content-bound proof: change a single byte of the document afterward and verification fails. Your client can confirm the signature — and that the contract wasn't altered after you signed — at attachkit.com/verify, and the check also runs offline. That's a real answer to "how do I know this is the version you signed?" It's PAdES-aligned, not a Qualified Electronic Signature (see the next answer).

Are these signatures legally valid for a client contract?

AttachKit produces PAdES-aligned signatures suitable for ordinary business and client agreements, plus a proof anyone can verify. Under the U.S. ESIGN Act and most contract law, an electronic signature you intend to apply is generally binding for everyday freelance work. It is NOT a Qualified Electronic Signature (QES) under eIDAS and is not on the Adobe Approved Trust List — if a specific counterparty or jurisdiction requires a qualified certificate, use a QES provider. We say this plainly so you can match the tool to the job.

Can I redact a rate or a previous client's name before I forward a doc?

Yes. Draw redactions yourself, or let optional AI suggest likely PII (it sends only the extracted text, never the file). Export with forensic scrub so the text and image content underneath is removed from the saved file — not just hidden behind a black box that can be copied out. Re-open and search the export to confirm before you send it.

Can the AI agent tidy up a contract PDF without uploading it?

Yes. The Private PDF Agent (in beta) edits the PDF inside your browser — the file is never uploaded. When you describe a change ("delete the blank last page", "add page numbers"), only the extracted page text is sent to the AI so it can locate things — never the document itself. The agent proposes a plan you review and approve; it never changes the file on its own, and your original is untouched.

Is any of this tax or legal advice?

No. AttachKit is software for working with PDFs. Filling a W-9 or signing a contract with it is not tax or legal advice, and using the tool creates no professional relationship. For how to complete a form correctly for your situation, check the current IRS instructions or a professional. You remain responsible for what you sign and send.