Compress PDF with digital signature
A digital signature is a hash of the file exactly as it stood when it was signed, and compression rewrites the file — so it does not survive, here or anywhere that genuinely makes the file smaller.
- Runs on
- Our server
- Cost
- Free, 5 a day
- Account
- Not needed
- Watermark
- None
Your browser would not let the file travel between pages (private mode does this) — open Compress PDF and drop it there instead.
What happens to your file
One step on our server.
The file goes over for the single step that needs it and is deleted the moment the job finishes. It is never stored, no third-party service is in the path, and five runs a day are free without an account.
Measured by really compressing it — the size shown is the size you get.
A scan shrinks by softening its pictures. Text stays sharp; photographs do not.
- No watermark The result is your file, unmarked. There is no paid tier that removes something we put there.
- No account Free five times a day without one, twenty with. The tool itself is identical either way.
- No ads, no waiting No banners, no upsell pop-up, and no invented thirty-second queue standing between you and your download.
- Nothing to install It is a web page. The same one works on a phone: no app, no extension, no browser plugin.
- What it reads PDF. Anything it cannot read is turned down with a reason on screen, not a silent nothing.
No file at hand? Open Compress PDF anyway →
How the workspace works
It plays on its own. Tap a step to hold it there.
read here, not uploaded the preview updates as you change it sent for this one step server copy deleted A drawing of the workspace — not a screenshot.
Why it breaks, and why it breaks every time
A certificate-based signature covers a byte range of the document. Verification re-reads those bytes, hashes them, and compares. Compression re-encodes the images and rebuilds the object table, so almost every byte moves; the hash no longer matches, and the reader shows the signature as invalid. This is not a bug in a particular tool, and it is not a setting somebody forgot to add.
Compress here uses Ghostscript, which reconstructs a document from its own parse of it rather than editing the original in place. That is what makes it good at the job, and it is what makes the outcome certain rather than likely.
A tool can leave a signature intact only by never touching the signed bytes — appending its changes as an incremental update at the end of the file. That cannot re-encode an image, and images are where the size is. So the honest end of that trade is a file that still validates and is barely smaller.
Compress first, then sign
The order fixes it and nothing else does. Get the file to the size it has to be, then sign the version you are actually going to send. A signature applied to the final bytes stays valid, because nothing happens to the file afterwards.
If the document is already signed and you were not the one who signed it, it cannot be made smaller and kept valid at the same time — those are two different requirements of the same bytes. Ask whoever signed it for a smaller original, or send it as it is.
A drawn signature is not a digital signature
The two share a word and almost nothing else. A drawn signature is a picture of your name placed on the page; it makes a document look signed. A digital signature is a certificate binding the file to an identity, and it is the thing a validator checks.
Fylevia’s Sign PDF draws. It puts your signature, your initials, a date or a typed line onto the page, which is the right tool when somebody needs to see a signature. It does not issue certificates and does not claim to. A document that validates in a reader comes from a certificate authority or your organisation’s signing setup, not from here.
Eleven questions
Questions
Is there any compressor that keeps a digital signature?
Not one that meaningfully compresses. Keeping the signature means not altering the signed bytes, which rules out re-encoding the images — and the images are almost always where the size is. A tool that promises both is either re-signing the file with its own certificate, which is a different signature from the one you had, or saving you very little.
My PDF is already signed and it is too big to send. What now?
The two requirements are in conflict, so something has to give. If you signed it, compress the unsigned original and sign that instead. If somebody else signed it, ask them for a smaller version — they can compress before signing. If neither is possible, send it as it is, or send it a way that takes the size: a link, a shared drive, or split into parts, which also breaks the signature and should be agreed first.
Does Fylevia’s Sign PDF give me a digital signature?
No. It draws a signature onto the page — your handwriting, your initials, a date, a typed line. That is the right tool when somebody needs to see a signature. It is not a certificate and will not validate as one, and we would rather say so here than let the word do the work.
Is Compress PDF free?
Yes. Free five times a day without an account, twenty with one, and no watermark either way.
Does my file get uploaded?
The file goes to our server for the one step that needs it, is processed, and is deleted the moment the job finishes. It is never stored, and no third-party service is in the path.
Do I need an account?
No. An account only raises the daily allowance from 5 to 20. The tool itself is identical.
Will it add a watermark?
No. The result is your file, unmarked. There is no paid tier that removes something we put there, because we do not put anything there.
Does it work on a phone?
Yes. It is the same web page, laid out for a small screen. Nothing to install, no app and no browser extension.
Are there ads, or a queue before the download?
No. No banners, no upsell pop-up, and no invented delay. When the job is done the file is ready.
Can it compress a PDF to an exact size, like 100 KB or 2 MB?
Yes. Type any number and it aims at exactly that, and the size shown before you download is measured by really compressing the file rather than predicted from a curve. What it cannot do is beat the format: a PDF’s fonts, page tree and cross-reference table survive any setting, so the floor is roughly a twelfth of what you started with. A 5 MB scan will not become 100 KB, and you are told so before you press anything rather than handed something larger than you asked for.
Will compressing make it blurry?
Text stays sharp: it is not an image and is not re-encoded. Photographs and scanned pages are, and that is where the size goes, so the smaller you ask for the more detail those lose. It is not reversible, so keep the original.
Open Compress PDF
Free, no account needed — the server copy is deleted right after.