There is no truly unlimited free online PDF editor. Every honest list ends in 'free up to a point'. Below are five editors where the free point is actually usable.
No bait-and-switch — caps are stated upfront.
Flint
Free tier for light editing and signing. No watermark. Day pass for heavier one-offs. Edit-pdf, sign-pdf, merge-pdf covered free for occasional use.
Sejda
Three tasks per hour, file size up to 200 pages or 50MB. No watermark. Most generous free tier in the category.
Smallpdf
Two tasks per day on free. Brand polish. Cap hits faster than Sejda.
iLovePDF
Generous free for some tools, capped for others. Broad toolset on free tier.
PDF24
Fully free with display ads. No daily cap. Trade attention for money.
Best for…
Genuinely occasional: Sejda. Light editing/signing: Flint. Maximal free toolset: PDF24 (if you tolerate ads).
FAQ
Which is genuinely free without compromises?
None completely — each trades something (tasks, file size or ads). Sejda's trade-off is the smallest for most users.
Do any watermark output?
PDF24, Sejda, Smallpdf, iLovePDF and Flint do not watermark output on free.
When should I pay?
When you hit a cap more than once a month. A day pass on Flint is the cheapest next step.
Free until you hit a wall. When that day comes, a Flint day pass costs less than committing to anything monthly.