Sejda is a more feature-rich tool than most free PDF sites, with page numbering, form filling, and a redaction tool among a long list of others — closer in scope to what PDF Vault is trying to cover than a bare merge-and-split site is. It is also, on the web, a server-based tool: your file has to reach Sejda's infrastructure before anything happens to it, and the free tier meters that usage directly.
The free tier's actual limits
Sejda's free web plan caps usage at 200 pages or 50MB per task, and three tasks an hour. For a single contract or report that is plenty. For a busy day of document work — several productions, a batch of scans, back-to-back conversions — it is easy to hit the hourly cap and have to wait, or pay.
PDF Vault has no equivalent cap, for a structural reason rather than a generous one: there is no server metering usage, so there is nothing to throttle. The free plan's limit is three operations a day, applied per browser rather than per file size or task type — a different tradeoff, not a strictly better or worse one, but worth knowing before you compare the two on "free tier" alone.
Where Sejda is genuinely better
Feature depth in a few areas. Sejda's form-filling and some of its conversion tools are more mature than PDF Vault's equivalents, reflecting a longer track record with more edge cases handled.
A desktop option. Sejda offers a downloadable desktop application for people who prefer an installed app to a browser tab, which PDF Vault — deliberately browser-only, so there is nothing to install or update — does not offer.
No local hardware ceiling. Because Sejda processes on its servers, a low-powered laptop or an old Chromebook is not a limiting factor the way it can be for any browser-based tool working on a large file.
Where local processing wins
No task-rate limit tied to file size. Because nothing is uploaded, there is no per-task page or size cap to hit in the middle of a busy day.
Confidential documents. No retention window, no third-party storage, no upload to explain to a security team or justify under a data protection policy.
Genuine offline use. Install PDF Vault as a Progressive Web App and every tool works with no connection at all — not possible for a server-based tool at any price.
Verifiability. Open the Network tab and confirm nothing is sent, on any operation, any time. A server-based tool's privacy claims can only be taken on trust, because the file genuinely does reach their infrastructure.
Pricing
Sejda's paid plan removes the page and task caps; check its current price before deciding, since plans change. PDF Vault Pro removes the daily operation limit from $10 a month billed yearly, with no account required for the free tier.
How to decide
Choose Sejda if you specifically need its form-filling depth, want a desktop app, or are working on hardware too limited to comfortably process large files in a browser tab.
Choose PDF Vault if you handle anything confidential, want a tool with no per-task caps to negotiate around, or want to be able to verify — not just be told — that your files never leave your device.