Overview

ComprimirPDF (comprimirpdf.app) is a free Spanish-language online PDF compressor that works locally in your browser. You choose a PDF, pick a compression level and download a smaller copy, and the site states that the document never leaves your device. No registration is needed.

How it works

Select a PDF or drag it onto the tool.
Choose one of three levels: Recommended, Better quality or Maximum compression.
Compare the original and new sizes, then download the result if it is smaller.

The tool re-encodes images that can safely be made smaller and saves the document structure more compactly. Text stays as text, vector graphics are not flattened into images, and the page count is preserved.

Choosing a level

The site gives sensible advice. Recommended suits email attachments, form uploads and on-screen reading. Better quality keeps more detail in photos, diagrams and small screenshots, which matters if people will zoom in or print. Maximum compression prioritises a light file and may make image artefacts visible. It suggests keeping the original, compressing a copy and opening it; if a photo, drawn signature or text inside a screenshot loses clarity, try a gentler level.

Honest about limits

A strong point is how clearly the site explains results. Page count does not predict file size; most weight usually comes from embedded photos or screenshots, so photo-heavy files shrink more than text-only ones. A PDF may already be optimised by a scanner or design app, leaving little to remove. If the compressed copy is not smaller than the original, ComprimirPDF does not offer a download, which avoids replacing your file with one that is the same size or larger. It also warns that compression creates a new file, so digital signatures may be invalidated, and recommends checking photos, small print, links and form fields before you share.

Pricing

Free to use, with no sign-up.

Who it suits

Spanish-speaking users who need to get a PDF under an upload or email size limit, such as for job applications, government forms or university portals, and who prefer not to upload sensitive documents to a server.

Pros: processing stays on your device; three simple levels; no download offered if the file doesn't shrink.
Cons: Spanish-only interface; one PDF at a time; limited savings on text-only or already optimised files.