Does c15t support Google-certified CMP like Ketch?

No, per vendor docs. Ketch documents Google-certified CMP support. c15t does not.

Do c15t and Ketch block trackers before consent?

Both held trackers back in every check. Each check loads the page. Then it looks for trackers that ran, cookies that the page set or data that left the page before the visitor chose.

c15t vs Ketch: cookie banner speed and features compared

Results forFramework

On desktop, c15t showed its banner sooner, in a median 60 ms against 1.68 s for Ketch. Ketch delayed the main content 16 ms less. Both held trackers back in every check. Per vendor docs, only c15t offers self-hosting. Per vendor docs, only Ketch offers a Google-certified CMP.

c15tinth

c15t Tested: 3.0.0-alpha.10
All c15t results

KetchKetch

Ketch Tested: Hosted
All Ketch results

Which is faster, c15t or Ketch?

Shorter bars are better. The exception is tracker blocking, where the bar shows the share of checks passed.

c15t and Ketch on the desktop profile, Next.js 16
Question	c15t	Ketch	Difference
Banner appearsTime from navigation until the banner is visible on screen. Lower is better.	60 msFast	1.68 sSlow	c15t’s banner appeared 1.62 s sooner.
Page slowed byExtra time before the main content paints (LCP), compared with the same page without a consent manager.	+16 ms95% interval 8 ms to 40 msSmall	0 msSmall	Ketch delayed the main content 16 ms less.
Click responds inTime from pressing Accept until the screen updates. Under 200 ms feels instant.	16 msOne visit measuredFast	40 msOne visit measuredFast	c15t responded 24 ms sooner. Both are under 200 ms, which feels instant.
Blocks trackersChecks that no tracker runs, the page sets no cookie and no data leaves the page before the visitor chooses.	4 of 4 checks passedBlocked	4 of 4 checks passedBlocked	Both held trackers back in every check.
Adds to pageExtra data transferred during the first load, compared with the same page without a consent manager.	+112 KB95% interval: 112 KBModerate	+532 KBHeavy	c15t added 420 KB less to the first load.

“About the same” means that the two results fall within each other’s spread. We measure both against the same page without a consent manager. We do not publish a direct head-to-head interval yet.

Page vitals and load times

Lab detail for engineers. All values are medians on the desktop profile. Both CMPs ran on Next.js 16.

Page vitalsChange against the same page without a consent manager.
Metric	c15t	Ketch
TTFB	+17 mspage 22 ms	0 mspage 5 ms
FCP	+28 mspage 92 ms	−4 mspage 60 ms
LCP	+16 mspage 148 ms	0 mspage 116 ms
CLS	No measurable shiftpage 0.00	No measurable shiftpage 0.00

Load timesMilliseconds from navigation.
Metric	c15t	Ketch
CMP script requested
CMP script loaded
Consent state known	166 ms
Banner visible	60 ms	1.68 s

After AcceptMilliseconds from the click.
Metric	c15t	Ketch
Screen responds	16 ms	40 ms
Banner gone
Consent applied
Analytics active

Which features differ between c15t and Ketch?

Statuses come from each vendor’s documentation. Each status links to its source.

Verified by test
Per vendor docs
Partial
Not supported
Unknown

Features that differ between c15t and Ketch, from vendor docs
Feature	c15tc15t	KetchKetch
Only c15t · 2
Self-hostableDeveloper	Per vendor docs (vendor documentation, opens in a new tab)	Hosted service (vendor documentation, opens in a new tab)
First-party SDKsFrameworks	React, Next.js, Vue, Nuxt, Svelte, SvelteKit, Astro, TanStack Start (vendor documentation, opens in a new tab)	Script tag only (vendor documentation, opens in a new tab)
Only Ketch · 1
Google-certified CMPStandards	Not on Google’s list (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)

Same on both · 13

Features with the same status for c15t and Ketch
Feature	c15tc15t	KetchKetch
IAB TCFStandards	Per vendor docs (vendor documentation, opens in a new tab)	TCF v2.2 (vendor documentation, opens in a new tab)
IAB GPPStandards	GPP 1.1 (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
Google Consent Mode v2Standards	Per vendor docs (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
Global Privacy ControlStandards	Per vendor docs (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
Geo-targeted bannersCompliance	Per vendor docs (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
Script blockingCompliance	Per vendor docs (vendor documentation, opens in a new tab)	Tag orchestration (vendor documentation, opens in a new tab)
Consent recordsCompliance	With a backend (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
Cookie scanningCompliance	Via Inth Website Audit (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
Open sourceDeveloper	Apache-2.0 (vendor documentation, opens in a new tab)	SDKs and samples only (vendor documentation, opens in a new tab)
Headless UIDeveloper	Per vendor docs (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
TypeScript typesDeveloper	Per vendor docs (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)
Free tierPricing	Open source; hosted free plan (vendor documentation, opens in a new tab)	5,000 users (vendor documentation, opens in a new tab)
Script tagFrameworks	Per vendor docs (vendor documentation, opens in a new tab)	Per vendor docs (vendor documentation, opens in a new tab)

Should you choose c15t or Ketch?

We built these lists from the measured and documented differences above. Neither list is a recommendation.

Choose c15t if

You want self-hosting
You want a first-party SDK for React, Next.js, Vue, Nuxt, Svelte, SvelteKit, Astro and TanStack Start
A fast banner matters to you: c15t’s banner appeared 1.62 s sooner
Page weight matters to you: c15t added 420 KB less to the first load

Choose Ketch if

You need a Google-certified CMP
Page load time matters to you: Ketch delayed the main content 16 ms less

What was tested?

Deployment: Both ran as hosted services. c15t ran against the hosted inth backend, not a local mock. Ketch ran from its vendor-hosted service. Network distance to each vendor is part of the result.

How we test: methodology cookiebench-v3.2.4