Starting today (May 27, 2026), every new SelectPdf API key is created with Chromium set as its default rendering engine. Existing keys are not affected — they keep behaving exactly the way they do today. This post explains what changes, why we picked Chromium, and how to choose a different engine on any call.
The short version
- New API keys (created 2026-05-27 onwards) now use
engine=Chromiumby default when the caller doesn’t specify one. - Existing API keys keep their current behaviour: when the caller doesn’t specify an engine, the historical
engine=WebKitdefault still applies. - Every caller can still override on a per-request basis by passing
engine=WebKit,Restricted,BlinkorChromiumon the conversion call.
Why Chromium
SelectPdf ships four rendering engines: WebKit (classic and Restricted), Blink, and Chromium. Chromium is the newest of the four — added in Select.Pdf 26.2 — and it’s the one we recommend for new integrations. Three reasons drove the change.
1. The most modern web platform support
Chromium is built on the same engine that powers Google Chrome and Microsoft Edge. That means strong, current support for modern CSS (grid, custom properties, container queries), modern JavaScript, web fonts, and the kinds of complex layouts that single-page apps and dashboards produce. Pages that render correctly in a recent browser tend to render correctly through Chromium without surprises.
2. Fast on real-world content
Chromium handles content-heavy pages — pages with substantial CSS, JavaScript, web fonts, or large images — comfortably. In our internal testing it consistently performs well on the kinds of complex layouts that single-page apps and modern dashboards produce, where older rendering engines spend more time on layout and re-flow.
3. Active engine line
Chromium and Blink are both actively maintained Chromium-family engines. The WebKit and WebKit Restricted engines are still supported and still ship in every release — but the modern web stack moves quickly, and new web features land in the Chromium family first. Defaulting new keys to Chromium means a fresh integration starts from the most modern baseline.
What this means for existing customers
Nothing changes for your existing integrations. If you have a SelectPdf API key today and you call /api2/convert/ without an engine parameter, your conversions still go through WebKit, exactly as before. Output bytes, pagination, and timing stay the same. Your code does not need to change.
If you’d like to try Chromium on your existing key, the simplest path is to add engine=Chromium on a single conversion call and compare the output. The parameter accepts WebKit, Restricted, Blink and Chromium, and it always wins over the per-account default — so you can A/B engines from your application code without touching any account configuration.
Once you’re happy with the result, you can either keep passing engine=Chromium in your client code, or contact support@selectpdf.com and ask us to update your default. After that, calls without the engine parameter will use Chromium too — and you can still override per-request whenever you need to.
FAQ
Will my PDFs look different?
Not unless you ask for it. If you don’t pass engine=Chromium on your calls and you haven’t asked support to change your default, output is byte-identical to what you’ve been getting all along.
Can I keep using WebKit?
Absolutely. Pass engine=WebKit explicitly on every conversion call, or leave your account as it is. All four engines remain fully supported — we are not deprecating any of them.
When would I still pick a different engine?
Chromium is a great default, but the other engines remain the right choice in specific cases. Blink is the other modern Chromium-family engine and is a reasonable alternative if you want to compare. WebKit and WebKit Restricted can be the right pick when you need to reproduce output byte-for-byte against a long-standing integration that was built against them, or when a particular page renders the way you want under WebKit and you’d rather not re-validate the visual baseline. Add engine=... to the call to try any of them; it’s a one-line change.
Does the demo endpoint use Chromium?
Yes — the keyless demo endpoint at /api2/convert/demo/ already runs every request on Chromium, and has done since the demo endpoint launched. This change brings new paid keys in line with what the demo has been doing all along.
Questions about the change, or want your existing key migrated to a different default? Get in touch: support@selectpdf.com.