How MythosPDF keeps your PDF intact. It only changes what you changed.
Most editors rebuild your page when you edit it. MythosPDF does the opposite: it treats your PDF as something to protect. The rule behind everything it does is simple. If you didn't ask for it to change, it doesn't change.
- Anything you didn't edit is locked in place
- Positions are measured precisely, never guessed
- Every page is checked against the original before you download
- Free, really
No trial, no watermark, no credit card.
- Private
No account needed. Your file is deleted from our server automatically.
- Your fonts
Edits use the fonts already inside your PDF, not a lookalike.
- Checked for you
If an edit would damage your file, we tell you instead of downloading it.
How it works
Three steps. About a minute.
- 1
Read the page
We work out what's on each page: the lines, paragraphs, fonts, tables and pictures, and exactly where each one sits.
- 2
Fit your edit
Your new text is measured letter by letter in the real font. If it needs more room, we move as little as possible to make space.
- 3
Change and check
Only the text you edited is rewritten inside the PDF. Then we draw the page again and compare it with the original before you see it.
Locked unless it has to move
Everything you didn't edit is treated as fixed. Something next to your edit only moves if there's truly no other way to fit your text, and then it moves as little as it can.
Smallest change first
First we try to fit your edit in place. Then within its line, its paragraph, its column and finally its page. The smallest fix that works wins, so a one word change never turns into a redesign.
Real font measurements
Text is measured with the same font engines your computer uses, letter by letter. We never guess a width, and we never quietly swap your font for another one.
Edits the text itself
Instead of painting white over the old words, we rewrite the text inside the PDF's own page instructions, and keep its colour, position and styling exactly as they were.
Clear priorities
Every decision follows the same order: don't break the document, keep your meaning, keep it readable, then move as little as possible. A tidier layout is never worth a damaged file.
Checked on every download
We draw the page before and after your edit the same way and compare them. If anything outside your edit changed, we stop and tell you rather than hand you a worse PDF.
Most PDF editors paint over your page. We don't.
A typical online editor hides the old words under a white rectangle and types new ones on top in a different font. MythosPDF changes the words themselves and leaves the rest of the page alone.
| Feature | MythosPDF | A typical online editor |
|---|---|---|
| How the text changes | The actual words in the PDF are replaced | A white box is pasted over the old words |
| Fonts | Your PDF's own font, size and colour | Often swapped for Arial or Helvetica |
| Longer text | Wraps onto the next line, content below moves down | Runs off the edge or overlaps other text |
| The rest of the page | Left exactly as it was | Often redrawn or flattened into an image |
| Search and copy | Only your new text is there | The old words are often still hidden underneath |
| If something goes wrong | We tell you before you download | You find out after you send it |
Questions people ask
What does "zero mutation" mean?
It's our name for the rule above. The words you edit change, and so does anything that has to move to make room for them. Nothing else changes: no redrawn pages, no swapped fonts, no flattened images.
Why not just regenerate the page from HTML?
Because rebuilding a page loses what made it yours: the spacing between letters, the embedded fonts, sharp logos and exact positions. MythosPDF never turns your PDF into a template. Your original file stays the starting point.
Will my fonts and layout change?
No. Your new text uses the font that's already in your PDF, at the same size and in the same colour. We never swap it for a lookalike without asking you first.
What if my new text is longer than the old text?
It wraps onto the next line, just like in Word, and the content below moves down to make room. If the page fills up, the rest continues on a new page right after it.
Where is my file stored?
A copy stays in your own browser so you can come back and keep editing. Our server only keeps a working copy while you edit, then deletes it automatically. We never sell, share or read your documents.
Can I edit a PDF where no text can be selected?
Usually, yes. Files from Microsoft Print to PDF often draw every letter as a shape; MythosPDF rebuilds real text from those shapes so you can edit, copy and search it. Scans are edited directly too.
Can I edit a scanned PDF?
Yes, directly, with no conversion. Click a word on the scan and type; MythosPDF redraws only those words in the page's own font, ink and paper. Changes stay within a line, and if a word can't be changed invisibly (handwriting, or a stamp in the way) you're told why.
Guides and tips
All articles →PDF Reflow Explained: What Happens When Your Edited Text Gets Longer
PDFs don't reflow by themselves. Here's how MythosPDF rewraps paragraphs, moves only the content below, and adds continuation pages without touching the rest.
Can You Edit a Scanned PDF? Text PDFs vs. Image PDFs Explained
How to tell a scan from a text PDF in 10 seconds, and how MythosPDF now edits scanned pages directly, with no conversion to Word.
How to Edit an Invoice PDF: Change Dates, Amounts and Addresses
Fix a wrong date, address, reference or line item on an invoice PDF in under a minute, with totals kept aligned and your billing tool's layout intact.
Ready to fix your PDF?
Free, in your browser, and it takes about a minute. No account needed.