Our own measurement
How heavy is your CAPTCHA?
Vendors publish prices, not page weight. So we measured it: every request each provider makes, compressed, as it travels to the visitor.
Measured on September 4, 2026 · Chromium, cold profile, each vendor's own demo page
| Tool | Loaded from the vendor | Of that, JavaScript |
|---|---|---|
| Cloudflare Turnstile | 27.5 KB | 27.5 KB |
| SilentShield | 47 KB | 47 KB |
| Google reCAPTCHA v2 | 423 KB | 346 KB |
| Google reCAPTCHA v3 | 459 KB | 348 KB |
| hCaptcha | 742 KB | 544 KB |
- Cloudflare Turnstile — Measured on: demo.turnstile.workers.dev
- SilentShield — Measured on: api.silentshield.io/assets/lib/behavior-captcha.js + client.js
- Google reCAPTCHA v2 — Measured on: google.com/recaptcha/api2/demo
- Google reCAPTCHA v3 — Measured on: recaptcha-demo.appspot.com
- hCaptcha — Measured on: accounts.hcaptcha.com/demo
Turnstile is lighter than we are
It is the first row of the table, not a footnote. Turnstile transfers 27.5 KB, we transfer about 47 KB — the behaviour module plus its loader. If every kilobyte on your page is contested, that is a real argument against us. Against reCAPTCHA and hCaptcha the gap runs the other way, by a factor of nine and sixteen.
How we measured
- 1Chromium with a fresh profile and an empty cache, driven by Playwright.
- 2Each vendor's own demo page — not our own test page, so nobody can claim a rigged setup.
- 3Every request going to that vendor's hosts, counted via the Chrome DevTools Protocol (encodedDataLength): the size over the wire, compressed.
- 4Repeated for the invisible reCAPTCHA v3 variant, because "invisible" is often assumed to mean "light".
Two traps that make other comparisons wrong
- Do not weigh one file. reCAPTCHA's api.js is a 1 KB bootstrapper; the file it pulls in weighs 345 KB. Weighing the loader gives you 1 KB.
- performance.getEntriesByType('resource') is not enough. Without a Timing-Allow-Origin header, third-party resources report a body size of 0 — hCaptcha looked like 2.5 KB instead of 742 KB.
Why page weight is not a detail
A CAPTCHA loads on the page where someone has decided to contact you or to buy. Every kilobyte competes with the form itself — on a phone, on a slow connection, at exactly the wrong moment. And weight is the one property a vendor cannot talk away: you can measure it yourself in ten minutes.
Check it yourself
Open the vendor's demo page, record the network traffic, filter by their hosts and add up the transferred size. If your numbers differ from ours, we want to know — the method above is written down so it can be repeated.
The lightest option is not always the quietest
SilentShield asks the visitor nothing at all: no puzzle, no cookie, no interruption — and the assessment stays in the EU.
See how it works