Klar vs. Fathom

Feature comparison

Pricing comparison

Prices are in EUR for Klar and USD for Fathom (both products bill in their primary market's currency as of 2026-09-03). Fathom has no free plan — pricing tiers below are pulled from Fathom's public pricing page.

Caveat: both price by pageviews, but count them differently. Fathom's limit includes custom events; Klar's counts pageviews only — custom events and the automatic ones (scroll depth, time on page) don't consume quota — so the same headline number goes further here. Sites are capped per tier on both: Fathom bundles 50 on every paid plan, Klar gives 3 free, 10, 50, then unlimited. If you run one high-traffic site, compare on pageviews. If you run many low-traffic sites, compare on sites-included.

When Klar wins

• You want to try before you pay — Klar's free tier (100,000 pageviews/mo across 3 sites) needs no card; Fathom's only free option is a 7-day trial.
• You run a SPA-heavy product — Klar's built-in pushState/replaceState instrumentation auto-detects route changes; Fathom's generic SPA mode needs manual setup when there's no framework-specific integration.
• You need rich event payloads — Klar's custom events support up to 50 properties per call.
• You want richer event properties at the same page weight — the two trackers are within 200 bytes of each other (~1.9 KB vs ~2.0 KB gzipped), so the embed cost is not the deciding factor; what each one can report is.
• You want anonymous identification with persistent properties (e.g. "this visitor logged in 3 times last month" without ever storing an email or IP) — Fathom stays fully anonymous with no identify concept.

When Fathom wins

• You want forever data retention without upgrading — every Fathom tier, including entry, retains data forever; Klar's free/Starter tiers cap retention at 30–90 days.
• You run many low-traffic sites on one account — Fathom bundles 50 sites into every paid tier at a flat rate; Klar bills per event regardless of site count, which can add up faster for a large multi-site agency portfolio.
• DNT is set up once and forgotten — Fathom's DNT honoring is a documented setup option; functionally similar to Klar's data-honor-dnt attribute once configured.
• You want built-in ecommerce revenue events — Fathom ships this as a named feature; Klar covers the same ground via generic custom event properties.

How we verified this

• Klar facts cross-checked against docs/PRODUCT.md and the source code under src/.
• Fathom facts cross-checked against usefathom.com/pricing (including the pricing tier data embedded in the page) and usefathom.com/features as of 2026-09-03.
• Pricing converted at the spot rates the products publish in (no FX conversion assumed).
• Where this page disagrees with the vendor's own marketing, the vendor's site wins — please tell us if you spot a discrepancy.