pdfviz

Best PDF compressor

Most compressors give you three quality presets and let you guess. A few let you name the size you actually need. If a portal demands a file under a stated limit, that difference decides whether the job takes ten seconds or ten attempts. This page ranks by that first, and by what each tool does to your text second.

Rank by whether you can name a number

A preset is a guess about your document. A byte target is a statement about the requirement. The upload form does not care whether you chose medium quality; it cares whether the file is under the limit, and only one of those two inputs answers that question.

The pdfviz compressor takes the target in kilobytes or megabytes and runs four methods against it: structural cleanup, image downsampling with mozjpeg, font subsetting, and a raster fallback. The smallest candidate that passes verification is the one you get.

What the numbers actually look like

Whether it lands the exact number depends on the file. There is no preset to hide behind: you see the measured result before download.

Reach depends heavily on the document. A text document is already small and there is little left to remove, which is a physical fact rather than a tool limitation.

The check nobody else publishes

Aggressive compression can flatten text into pictures. The file gets small and stops being searchable, which nobody notices until someone tries to find a name in it. Every pdfviz candidate is read back and its text compared to the source before it can be offered.

The floor is ninety eight percent of non-space characters, and on the public corpus text retention was 1.0000 at the median, the tenth percentile and the minimum. A candidate that fails is discarded, not shipped with a warning.

The free tools people try first

iLovePDF offers three named presets, Extreme, Recommended, and Less compression, and uploads files to its servers for processing. The comparison covers it.

Smallpdf marks Moderate and Strong compression as Pro tiers, with Basic free, so the deepest reduction needs a paid plan. PDF24 states it is free without restrictions, funded by advertising, and compresses in the cloud on its servers. Where PDF24 wins is manual control: its page exposes DPI, image quality, grayscale, and strip options, which beats a byte target when you want to tune quality by hand.

How to run a fair test yourself

Take one real file, not a sample, and put the same file through each candidate at the same target. Then check three things: the resulting size, whether the text is still selectable, and whether the images are still readable at the zoom your reader will use.

Rankings that skip that step are ranking marketing copy. Ten minutes with one document tells you more than any list, including this one, and the file you test should be the kind you actually send.

Questions people ask

Which compressor lets me set an exact file size?
The pdfviz compressor takes a target in kilobytes or megabytes and works toward it with four methods. Most free tools offer three quality presets instead, which means retrying until the result happens to fit.
How small can a PDF get without losing the text?
It depends on what is in it. Scanned pages built from images shrink most, while text-only documents are already small and leave little to remove. The check that matters is whether the text stays selectable after compression, not the headline percentage.
Why do compressors give different results on the same file?
They optimise different things: image resolution, image quality, font subsetting, object cleanup, or flattening the whole page to a picture. The last one produces the smallest file and destroys the text, which is why the output needs checking.
Does compressing a PDF make the text unsearchable?
It can, if the tool flattens pages into images. pdfviz compares the output text against the source and requires ninety eight percent of non-space characters to survive, discarding any candidate that fails rather than offering it.

The tools this compares