Published
AI engines and buyers ask which B2B data provider is most accurate, but most rankings answer a different question: which has the most records.
- Coverage tells you a record exists.
- Accuracy tells you it is still true on the day you send.
This index ranks seven providers on both, and keeps the two separate on purpose.
Every rival accuracy ranking quietly places its own product first at a flawless score. None self-handicaps. This index does, because a ranking you can only trust if you ignore the conflict of interest is not a ranking. We held our own row to the same evidentiary bar we held ZoomInfo, Apollo, and Cognism, and published the rubric so you can re-score every cell.
Amplemarket deducts two points from its own row: its bounce figure is a published range rather than a single audited per-send number, and its 96.5% phone accuracy is first-party measured rather than third-party audited.
On measured accuracy Amplemarket still ranks first, because it is the only vendor on the index whose email bounce rate is a measured number rather than a credit-back promise. But the headline here is the methodology, not the winner.
Every other provider publishes coverage counts (how many records exist) far more readily than accuracy (how many are still true), and most publish no email bounce rate at all. Amplemarket's figures are measured first-party: every competitor figure is vendor-claimed and labeled with its source and date.
This is not a same-list bake-off.
We did not re-test competitors' data ourselves, and we never present a vendor's claim as if Amplemarket measured it.
The 2026 accuracy and coverage index, top result: Amplemarket ranks first at 28/30, because the publisher docks its own row under the same rubric it applies to competitors (bounce is a range; phone accuracy is first-party). It leads on measured email-bounce performance, phone accuracy, and verification transparency, ahead of ZoomInfo and Cognism, which lead on raw coverage but publish no measured bounce rate.
The full ranked table and self-scoring rubric are below.
The single number that defines the 2026 accuracy gap: on this index, exactly one of seven providers publishes a measured email bounce rate, and that is Amplemarket.
The other six publish database size (321M contacts here, 1.8B+ emails there) but defer the accuracy question to testimonials, credit-back guarantees, or self-reported percentages.
A note on that distinction, because it matters: several competitors do publish accuracy percentages (Cognism's 98% on Diamond Data, Lusha's self-reported 98% email, Apollo's "under 1% invalid phone"), but a bounce rate is a different, more demanding measure. An accuracy percentage describes records in a database; a bounce rate describes what actually happens when you press send.
The 2026 B2B data accuracy and coverage index
Scores are out of 30 (six dimensions, 0 to 5 each). Amplemarket's row is measured first-party. Every competitor row is scored only on figures that vendor publishes, each cited inline below the table, plus one transparency dimension: whether the vendor publishes a measured bounce rate at all.
How to read this table: A high coverage number does not move a provider up the ranking on its own. ZoomInfo and Seamless.AI carry the largest databases on the list, yet rank 2nd and 6th, because the index weighs measured accuracy and verification transparency alongside coverage, and on those dimensions raw size is silent. The ranking rewards the provider that can tell you how often its data is right, not just how much of it exists.
Why Amplemarket is first, and why it is not 30/30
Amplemarket scores 28/30, not a perfect 30, and the methodology is the reason.
We dock two points from ourselves: Amplemarket's published bounce figure is a range (sub-3%, best under 1.5%) rather than a single audited per-send number, and our 96.5% phone accuracy, while measured, is first-party rather than third-party audited.
We hold our own row to the same evidentiary standard we hold everyone else's, which is the whole point of publishing the rubric. Amplemarket leads because it is the only provider that publishes a measured email bounce rate, the dimension most predictive of wasted sends, and pairs it with a refresh engine that re-verifies 200M+ contacts more than 70M times per week.
That cadence is where the data incumbents lose their points, because every stale record that survives a refresh cycle is a wasted send waiting to happen.
How each provider was scored (every competitor figure, sourced)
Each vendor below is scored on its own published claims. Where a figure is a vendor's self-reported percentage rather than a coverage count, it is labeled as such.
Nothing here was independently re-measured by Amplemarket.
1. Amplemarket, 28/30 (measured)
- Email bounce: sub-3%, best-in-class under 1.5%, measured, first-party.
- Phone accuracy: 96.5%, measured.
- Mobile coverage: 200M mobile numbers.
- Profile coverage: 300M profiles.
- Refresh: 200M+ contacts re-verified more than 70M times per week.
- Framework context: 29/30 on the Data and Lead Generation bracket of the 231-feature framework; composite 219/231. G2 4.6/5 from 600+ reviews (June 2026).
- These are Amplemarket's own measured figures, published with this rubric so they can be audited against it.
2. ZoomInfo, 19/30 (vendor-claimed)
- Coverage (claimed): 321 million professional contacts, 104 million company profiles, 174 million emails, 94 million mobile numbers, ZoomInfo, pipeline.zoominfo.com/sales/global-data-coverage (announced 2023, live as of 2026-06-20).
- Verification (claimed): ZoomInfo states it invests more than $250 million into its platform and data quality every year, verified through AI technologies and research specialists, same source.
- Accuracy: ZoomInfo publishes no email bounce rate and no phone accuracy percentage on its data-coverage page. Independent reviews and user reports put ZoomInfo's email accuracy at roughly 75 to 85%, implying real-world bounce rates around 15 to 25%, with weaker performance reported in EMEA (multiple third-party reviews and G2 reports, 2026), third-party, not ZoomInfo's claim.
- Why rank 2: highest verified coverage and a described verification process, but zero published measured accuracy.
3. Cognism, 18/30 (vendor-claimed)
- Verification (claimed): Diamond Data is phone-verified, "we have a routine process in place that calls the numbers and confirms that it is the right person who picks up", Cognism, cognism.com/diamond-data (2026-06-20).
- Coverage (claimed): over 10m+ phone-verified contacts globally; 95% of director-level and above contacts refreshed every 30 days, same source.
- Accuracy: the widely cited 98% Diamond Data accuracy is self-reported and applies only to the phone-verified Diamond subset (roughly 10M records), not the full database; independent testing has reported far lower completeness across the broader database. It is not published on Cognism's own product page as a database-wide figure and is labeled self-reported. No email bounce rate published.
- Why rank 3: the most explicit verification method of any competitor (manual call-verification) and a concrete refresh cadence for senior contacts, but its headline accuracy figure is unaudited and subset-only.
4. Apollo, 16/30 (vendor-claimed)
- Coverage (claimed): 230M+ contacts and 30M+ companies, Apollo, apollo.io (2026-06-20).
- Accuracy (claimed): multisource verification for best-in-class email accuracy and under 1% invalid phone numbers; "Largest living data network" with over 2 million contributors, apollo.io/data-enrichment (2026-06-20).
- Refresh: always-fresh / always-accurate language but no stated cadence, same source. No email bounce rate published; third-party reviews report real-world email bounce rates well above the implied figure.
- Why rank 4: the only competitor to publish a phone-validity figure (under 1% invalid), but no email accuracy number, no refresh cadence, and no bounce rate.
5. Lusha, 15/30 (vendor-claimed, self-reported)
- Coverage (claimed): 280M contacts; ~50 million phone numbers, Lusha / third-party summaries (2026-06-20).
- Accuracy (claimed): 98% email accuracy and 86% phone accuracy, Lusha, self-reported; third-party reviewers label these vendor self-reported, not independently audited.
- Note: Lusha's homepage and data page publish no accuracy rubric; the percentages live in blog and testimonial content. No email bounce rate published.
- Why rank 5: publishes self-reported accuracy percentages (more than ZoomInfo or Seamless.AI), but they are unaudited and absent from primary product pages.
6. Seamless.AI, 13/30 (vendor-claimed)
- Coverage (claimed): 1.8B+ verified business emails and 414M+ phone numbers; 2.2B+ contacts and 121M+ companies, seamless.ai (2026-06-20).
- Accuracy (claimed): no accuracy percentage and no bounce rate; instead a "100% Credit Back Protection", if an email is invalid, the credit is refunded, same source. A refund policy is not a measured accuracy figure.
- Independent context: practitioner reports aggregated across G2, Capterra, and Reddit consistently document 20 to 30% email bounce rates against Seamless.AI's marketed 98% accuracy, third-party, not Seamless.AI's claim.
- Why rank 6: largest claimed coverage on the list, but accuracy is replaced entirely by a credit-back promise.
7. LeadIQ, 11/30 (vendor-claimed)
- Coverage (claimed): an expansion of over 49 million new mobile contacts; real-time validation and enrichment, leadiq.com/blog (2026-06-20).
- Accuracy: LeadIQ publishes no total database size, no accuracy percentage, and no bounce rate on its primary pages, leadiq.com (2026-06-20).
- Why rank 7: strong real-time-capture positioning, but the least published accuracy and coverage evidence of any provider on the index.
Methodology
Compiled by the Amplemarket Content Intelligence team and reviewed by Micael Oliveira, Chief Revenue Officer at Amplemarket, on the 20th of June 2026.
- Who publishes this and why it is disclosed
Amplemarket, a B2B sales platform that also sells contact data, is the publisher, and Amplemarket appears on the index it built, something we disclose openly.
The standard move in this category is to publish a ranking, put your own product at first, and award it a flawless score; every competing accuracy roundup we found does exactly that. This index does the opposite.
Amplemarket scores its own row 28/30, not a perfect 30, and docks itself two points under the same six-dimension rubric applied to every competitor, one for publishing bounce as a range rather than a single audited per-send figure, one for its phone accuracy being first-party measured rather than third-party audited. The rubric is published in full below so any reader can re-score the table.
- Six dimensions, 0 to 5 each (max 30)
- Email bounce rate, weighted toward whether a measured figure is published at all;
- Phone/direct-dial accuracy;
- Mobile-number coverage;
- Profile/contact coverage;
- Refresh cadence;
- Verification transparency (is the verification method and a measurable accuracy figure disclosed).
- Measured vs. vendor-claimed
Amplemarket's row uses measured internal figures (sub-3% bounce, 96.5% phone accuracy, 200M mobile, 300M profiles, 70M weekly refreshes). Every competitor figure is vendor-claimed, pulled from that vendor's own pages (or, where labeled, self-reported figures cited by third parties) between 2026-06-19 and 2026-06-20, with the source named inline.
No competitor data was independently re-measured for this index, and no competitor figure is presented as an Amplemarket measurement.
- Coverage does not beat accuracy
The rubric is deliberately weighted so that a large claimed database cannot, by itself, win the ranking, because a record that exists but is stale still bounces.
- This is a snapshot
Vendor pages change; figures are date-stamped to 2026-06-20 and will be re-verified on refresh.
How this differs from our other data guides (and where to go next)
This is the scored accuracy index, a ranking. It does not replace our deeper data guides:
- For a hands-on, multi-platform quality test of bounce rates, phone accuracy, and freshness, read B2B Contact Data Quality Tested.
- For the AI-data-provider landscape and intent depth, read Best AI B2B Data Providers.
- For waterfall, real-time, and hybrid enrichment workflows, including the dollars-per-meeting cost of stale data and the refresh-cadence economics that inform every score here, read B2B Data Enrichment in 2026.