ZoomInfo vs Seamless.AI (2026): Data, Pricing and API Compared

ZoomInfo is the safer pick if you want a published price list and a documented API. Seamless.AI claims the bigger database and more mobile numbers, but it publishes no dollar price. At 1M records, neither tool has a public price.

Verdict

• Pick ZoomInfo if you want credit prices you can read, a free-to-start API with free search, and one suite with direct dials and signals (ZoomInfo pricing, September 2026).
• Pick Seamless.AI if reps will work inside its Chrome extension and calling tools, or if you want the largest claimed mobile-number pool and will negotiate price with sales (Seamless.AI; platform overview, October 2026).
• Pick neither if you pull people and company data by API at volume and want one flat monthly bill. LeadOcean is one option, covered below.

Side by side

All figures were checked in September 2026. Both vendors change plans and promotions often, so confirm on their pages before you buy.

Data and coverage

Seamless.AI claims the larger database, and ZoomInfo's own pages do not agree with each other. Seamless.AI lists 2.2B+ verified contacts, 121M+ companies and 448M+ verified mobile numbers. ZoomInfo's API docs claim 500M+ contacts, and its Sales page says 420M+.

These are vendor claims, and neither tool publishes a method. A bigger number can mean more stale rows as easily as more people. Run the same 100 lookups in both before you trust a count.

On phones, the claims point opposite ways. Seamless.AI says 448M+ verified mobile numbers. ZoomInfo's Sales page says 120M+ direct dials and gives no accuracy rate (ZoomInfo Sales, September 2026). Seamless.AI's figure is larger, but it is a claim too.

On filtering, ZoomInfo says you can filter on 300+ attributes (ZoomInfo Sales, September 2026). Seamless.AI's contact search takes 39 filter and modifier parameters, and company search takes 23 (Seamless.AI docs, September 2026).

Seamless.AI charges one credit per contact, and that credit covers the email and phone together. ZoomInfo also charges one data credit per record, but a record is charged once per 12 months (ZoomInfo docs, September 2026).

API and developer experience

ZoomInfo is the stricter API to start with, and Seamless.AI is the slower one to use. ZoomInfo needs an app, a client ID and secret, and a bearer token. Seamless.AI takes a key in a header, but a result comes back later by poll or webhook. Placeholders below stand in for real people.

ZoomInfo: get a token, then enrich a contact.

curl -X POST "https://api.zoominfo.com/gtm/oauth/v1/token" \
  -u "$ZI_CLIENT_ID:$ZI_CLIENT_SECRET" \
  -d "grant_type=client_credentials"

curl -X POST "https://api.zoominfo.com/gtm/data/v1/contacts/enrich" \
  -H "authorization: Bearer $ZI_TOKEN" \
  -H "content-type: application/vnd.api+json" \
  -d '{"data":{"type":"ContactEnrich","attributes":{"matchPersonInput":[{"personId":123456789}],"outputFields":["id","firstName","jobTitle","email"],"requiredFields":["email"]}}}'

ZoomInfo recommends a two-step flow. Search and lookup are free and return IDs. Enrich takes up to 25 records, and each record found costs one credit unless it is already under management. A "No match" is not charged (ZoomInfo docs, September 2026).

Seamless.AI: start a research job. It answers HTTP 202 with requestIds.

curl -X POST https://api.seamless.ai/api/client/v1/contacts/research \
  -H "Content-Type: application/json" \
  -H "Token: $SEAMLESS_API_KEY" \
  -d '{"contacts":[{"contactName":"Jane Doe","companyName":"Acme Corp","title":"CTO"}]}'

Next you call GET /contacts/research/poll with those IDs, or take the result by webhook. A poll ends in done, error, missing or duplicate (Seamless.AI docs, September 2026). The docs do not say whether a missing record is charged, and they give no job time.

Throughput differs more than the headline limits suggest. At 1M records, ZoomInfo needs 1,000,000 / 25 = 40,000 enrich calls, about 27 minutes at the Standard rate of 25 a second. On Builder at 5 a second it is about 2 hours 13 minutes, before the 10,800-an-hour cap slows it further.

Seamless.AI's limit looks tighter at 60 a minute, but each call carries up to 500 records. That is 2,000 search calls and 2,000 research calls, about 34 minutes each in separate windows, plus polling (Seamless.AI docs, September 2026). On request windows alone, Seamless.AI's bigger batches keep pace with ZoomInfo's faster limit.

Pricing

ZoomInfo publishes credit prices for self-serve buyers, and Seamless.AI publishes none. The worked examples below use the lowest published list price at the volume shown.

ZoomInfo's self-serve route is GTM AI data credits. List price falls with purchase size. It is $0.45 for 100 credits, $0.41 at 1,000 and $0.38 at 2,500 to 10,000. Then $0.32 at 15,000 to 20,000, $0.29 at 30,000 to 50,000 and $0.25 at 100,000 credits ($25,000). The slider stops there, and larger volumes go to Enterprise (ZoomInfo pricing, September 2026). This page quotes no platform plan price, because zoominfo.com/pricing returned a human check.

Seamless.AI's pricing page is a quote form. Licenses carry credits: Free has 50 with no refill, Basic 250 a month and Pro 10,000 a month, refreshed on the contract date (Seamless.AI credit docs, September 2026). Subscriptions are annual, and cancelling needs 60 days' notice before renewal or it renews for 12 months (Seamless.AI terms, September 2026).

At 10,000 records a month

• ZoomInfo: 10,000 data credits x $0.38 = $3,800 at list. A record is charged once per 12 months, so repeat lookups of the same contact cost nothing extra (ZoomInfo docs, September 2026).
• Seamless.AI: 10,000 contacts x 1 credit = 10,000 credits, which is one Pro license for a month. No public price (Seamless.AI pricing, September 2026).

At this size only ZoomInfo gives you a number you can plan around. Seamless.AI may cost less or more. You cannot tell until sales quotes you. Ask for the price per license, the bulk pool rate and the renewal terms in writing, because the contract renews for 12 months without 60 days' notice.

At 1M records a month

• ZoomInfo: no public 1M price. The slider tops out at 100,000 credits for $25,000. Ten of those would be $250,000, but that assumes the $0.25 rate holds and is not a quote. Do not multiply $0.38 by 1,000,000, because $0.38 is the $1,000 tier only (ZoomInfo pricing, September 2026).
• Seamless.AI: no public 1M price. 1,000,000 contacts x 1 credit = 1,000,000 credits, or 1,100,000 if each record first comes from a search at 1 credit per 10 results. A Pro license holds 10,000 a month, so that is 100 licenses or a bulk pool, both quote only (Seamless.AI docs, September 2026).

Seamless.AI says invalid emails are refunded automatically (Seamless.AI, September 2026). ZoomInfo's docs say a no-match or an error is not charged, and search and lookup are free.

Where ZoomInfo wins

• Credit prices anyone can read, from $0.45 down to $0.25, and a free tier with 1,000 data credits.
• Free search and lookup on the API, so you pay only to enrich a record you chose.
• Higher rate limits on paid packages: 25 and 35 requests a second.
• Direct dials and 300+ filter attributes in one suite, with signals sold alongside.
• No contract on GTM AI credits, and credits do not expire while the account is active.

Where Seamless.AI wins

• A larger claimed database: 2.2B+ contacts and 448M+ mobile numbers, against ZoomInfo's 500M+ and 120M+.
• One credit covers a contact's email and phone together.
• Bigger batches: 500 records per research request, against 25 on ZoomInfo.
• A Chrome extension and calling tools for reps, plus an MCP server with 57 tools (Seamless.AI platform overview, October 2026; Seamless.AI MCP docs, September 2026).
• Invalid emails are refunded automatically, by its own statement.

If you need volume through an API

LeadOcean is a data API and MCP server with no credits and no seats. It is not a sales suite, and it has no intent data. Pro costs $499 a month flat, with unlimited searches, enrichments and lookups. The Free plan gives 1,000 records one-off with no card, and both plans get the same REST API and 12-tool MCP server. POST /v1/exports returns up to 50,000 rows per request (LeadOcean exports docs, September 2026). Compare it on a list you already know, then read ZoomInfo alternatives and pricing.

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