Methodology

How data is collected

Every vendor entry is built by fetching that vendor's own pricing, help, and legal pages directly — not by summarizing from memory and not by copying other comparison sites. Every factual field carries a source_url and a verified_at date pointing at the page that fact came from. You can check any number on this site by clicking its "Source ↗" link.

When a fact can't be confirmed against a real source — a vendor's pricing page renders through client-side JavaScript that can't be read statically, a page blocks automated access, or a feature simply isn't documented anywhere — the field is left blank rather than guessed. That's a deliberate, visible gap, not an oversight: a "No source" or "Not verified" label on this site means exactly that, and an honest gap is worth more than a confident, wrong number.

Staleness

Every sourced fact shows the date it was last verified. Any field older than 90 days is flagged with an amber staleness indicator in the UI, and the site's data-validation script warns on it at build time. As of the last build, every tracked vendor's full review is within the last 90 days.

How the pricing estimates work

Vendor pages and the calculator don't read prices off a static table — each vendor has a small program (in pricing/) that models its actual pricing shape: contact-tiered, send-volume-tiered, pay-as-you-go, flat license plus infrastructure, or a hybrid of these. Every estimate carries a confidence level:

Exact

The price point was read directly and statically off the vendor's own pricing page.

Estimated

The figure is triangulated from third-party sources, interpolated between confirmed anchor points, or based on a disclosed modelling assumption (like amortizing a one-time license fee, or an approximate currency-conversion rate) — always spelled out in that result's caveats.

Unavailable

No number is shown at all — used for enterprise/quote-only tiers and anywhere a real figure exists but can't be verified. This site will show you nothing before it will show you a guess.

Estimates also exclude anything not modelled — paid add-ons like dedicated IPs or SMS, infrastructure costs outside the vendor's own billing (like the VPS a self-hosted tool needs), and enterprise overage terms. Every result lists these exclusions as caveats rather than silently folding them in or leaving them out unmentioned.

Monetization

Affiliate revenue is a direct conflict of interest for a comparison site, so the ranking logic is built to make that conflict structurally impossible rather than merely promising not to act on it. The calculator's ranking function only ever sees a vendor's cost — it is typed so that a vendor's affiliate status can't even be read from inside the code that decides ranking order. If the cheapest fit for your requirements pays this site nothing, it still ranks first.

Whether a vendor runs an affiliate program is tracked internally the same way any other fact is — sourced and dated — but it isn't displayed on vendor pages, and this site doesn't link to affiliate programs.