Convert PDF files to Compressed PDF instantly and privately. File Transmute runs entirely in your browser, so your PDF is never uploaded to any server.
Compresses your PDF entirely in your browser — nothing is uploaded.
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—Processed on your devicedrop a file
Conversions run entirely in your browser. Turn off your Wi-Fi and try it — it still works. Nothing leaves this device.
Compressing a PDF shrinks its file size so it's easy to email or upload, while keeping it readable. Most oversized PDFs are large because of the images inside them — scans, screenshots, and photos saved at full resolution. The text itself is tiny by comparison, so the fastest way to reduce a PDF is to recompress those images rather than touch the text.
File Transmute compresses your PDF in the browser: it re-renders each page at a screen-friendly resolution and re-encodes the images, then hands back a smaller file. Nothing is uploaded, so your document stays private — and there's no sign-up or daily limit. A 20 MB scanned PDF can often drop to a few megabytes with no visible difference at normal zoom.
It helps to understand "without losing quality." Truly lossless compression keeps every pixel identical but saves little; visually-lossless compression re-encodes images so slightly that you can't tell on screen, while cutting size dramatically. For email, web upload, and reading, visually-lossless is exactly what you want. If you may need to reprint at high resolution later, keep the original as well.
Compression works best on image-heavy or scanned PDFs. A PDF that's mostly text is already small, so there's little to gain. If your file is a stack of photos, consider splitting out just the pages you need first, or building a right-sized PDF directly with our Images to PDF tool.
Best for
Getting a PDF under an email or job-portal size limit
Shrinking a scanned document that's too large to upload
Reducing a photo-heavy PDF for faster sharing
Good to know
Compression reduces image resolution and removes redundant data while keeping the document readable. Text-only PDFs are already small, so the savings there are modest; the biggest gains come from image-heavy or scanned files.
Compress a PDF for email
Most email providers cap attachments at around 25 MB — Gmail and Outlook both bounce anything larger, and some corporate mail servers stop you well before that. A single phone-scanned document can easily blow past the limit, because each page is stored as a full-resolution photo. Compressing the PDF first re-encodes those page images at a sensible resolution, which is usually enough to bring a bulky scan back under the limit without you having to split it or zip it.
If the file is still too big after compressing, the problem is almost always page count rather than image quality. Use Split PDF to send only the pages the recipient actually needs — there is rarely a reason to email all 40 pages when the person asked for page 12.
Reduce PDF size for a job application
Job portals and applicant tracking systems (ATS) are stricter than email: many cap each upload at 2–5 MB, and some reject the file silently, so you never find out your CV or certificate did not go through. Scanned degree certificates, reference letters, and signed contracts are the usual culprits because they are images of paper rather than digital text.
Compress to the smallest size that is still comfortably readable on screen — a recruiter is viewing your document on a monitor, not printing it at full resolution, so screen quality is plenty. Open the compressed file and read it before you submit: you want to be sure a stamp, signature, or small-print clause is still legible.
Compress assignments for upload portals
School and university portals — Canvas, Google Classroom, Turnitin, Moodle — each set their own per-file limits, often in the 20–100 MB range but sometimes much lower for a single submission. Photographed homework and lab scans are the files that trip these limits, since a dozen phone photos combined into one PDF can be enormous.
Compressing the finished PDF gets it under the cap while keeping the pages readable for grading. If you are assembling photos into the PDF in the first place, converting them with JPG to PDF and then compressing is the reliable two-step: build the document, then shrink it.
What happens to PDF quality
It is only fair to be clear about the trade-off. Compression works by re-encoding the images embedded in the PDF at a lower resolution and stripping out redundant data — it does not touch the actual text, which stays sharp and selectable. So a text-heavy report compresses with no visible change, while a scanned or photo-heavy document gets softer the more you shrink it.
At normal reading zoom the difference is usually invisible. You will notice it if you zoom right in or print the file at full size. The safe habit: always open the compressed PDF before sending it, and keep the original if you might need to print or archive it later.
Why some PDFs compress more than others
The size of a PDF is dominated by its images. A scanned or phone-photographed document — where every page is a large picture — can often shrink by 80–95%, because there is a lot of redundant image data to squeeze. A PDF that is mostly digital text was already small to begin with, so compressing it might only save a few percent, and that is normal, not a fault.
A file that has already been compressed once will barely shrink again — the redundant data is gone after the first pass. If your PDF hardly changes size, it is almost certainly one of these two cases: it was text-based already, or someone compressed it before you.
Private PDF compression without uploading
Compression here runs entirely in your browser. The PDF is read, re-encoded, and saved on your own device — the live privacy panel on this page shows 0 bytes uploaded while it works, and you can turn off your Wi-Fi after the page loads and it will still compress. That is the real reason to use an on-device tool for this job: the oversized PDFs people most often need to shrink are bank statements, payslips, medical scans, and signed contracts — exactly the documents you would not want sitting on someone else's server.
Typical result — a phone-scanned multi-page contract
~40 MB
Before
~3–4 MB
After
~90% smaller
What this tool does
Input format
PDF
Output
A smaller PDF (same pages, re-encoded images)
Where it runs
In your browser — nothing is uploaded
File size limit
Bounded by your device's memory, not a fixed server cap
Batch
One PDF at a time
OCR
Not applied — existing text is left untouched
Text & metadata
Text stays sharp and selectable; redundant data is stripped
Works offline
Yes, once the page has loaded
Browsers
Chrome, Edge, Firefox and Safari — desktop and mobile
Typical time
A few seconds; large scans take a little longer
How to convert PDF → Compressed PDF
01
Drop your PDF file into the converter above — it stays on your device.
02
Choose Compressed PDF as the output. File Transmute picks the smartest settings automatically.
03
Click Convert and download your Compressed PDF file instantly.
Frequently asked questions
Compress it and check the result — image-heavy scans usually drop dramatically, often from tens of megabytes to a few, which clears the common 5 MB and 25 MB caps easily. If it is still too big, send fewer pages: use Split PDF to extract only the pages the recipient needs. A text-only PDF that is already small will not shrink much, because there was never much image data to squeeze.
No — the text stays sharp. Compression re-encodes the embedded images at a lower resolution, but it leaves the actual text vector-crisp and selectable. What can soften is a scanned page, because there the whole page is an image. At normal reading zoom it looks the same; you would only notice on a full-size print or a deep zoom. Open the compressed file before sending it to be sure.
Yes, and scanned PDFs are exactly where compression helps most — every page is a photo, so there is a lot of redundant image data to squeeze, and an 80–95% reduction is common. Compress to the smallest size that is still comfortably readable, and check that any stamp, signature, or small print is still legible before you submit it.
Almost always one of two reasons: the PDF was already mostly digital text (there was little image data to compress in the first place), or it had already been compressed once and the redundant data is gone. Both are normal. The big savings come from scanned or photo-heavy files that haven't been shrunk before.
This tool compresses one PDF at a time so you can check each result before sending it. If you have several oversized files, run them through one after another — nothing uploads, so there is no queue and no per-file wait.
No. Compression runs in your browser, so the file never leaves your device — which is what you want when the oversized PDF is a bank statement or a medical scan. The privacy panel on the page shows 0 bytes uploaded while it works.
