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

Seamless.AI and Coresignal both sell B2B data by the credit, but for different jobs. Seamless.AI is a sales app with an API added on and no public price. Coresignal is a data source for profiles, companies and job postings, with every plan priced in dollars.

Verdict

• Pick Seamless.AI if reps need a prospecting app and phones matter. One credit covers a contact's email and phone together, and it claims 448M+ verified mobiles. You get the price from sales.
• Pick Coresignal if you need job postings, company signals or licensed datasets. It lists 907M+ employee records and 482M+ job postings, and prints every plan from $49 a month.
• Pick neither if you need contacts at volume through an API at a price you can read. Neither publishes a 1M price. LeadOcean is one option: Pro is $499 a month, flat.

Side by side

Data and coverage

Seamless.AI claims more contacts. Coresignal claims more raw profiles and adds job postings. The two counts measure different things, so do not read them as one scale.

Seamless.AI lists 2.2B+ verified contacts and 121M+ companies. Coresignal lists 907M+ employee records, 70M+ companies and 482M+ job postings, and its homepage says company data is delivered daily (Coresignal, September 2026). Both are the vendors' own numbers.

Contact fields are the real gap. Seamless.AI claims 1.6B+ verified business emails and 448M+ verified mobiles (Seamless.AI, September 2026). Coresignal's multi-source employee records carry a professional email with four status levels: verified, matched_email, matched_pattern and guessed_common_pattern.

Its Base Employee API pages list no email field. No phone field appears in either Coresignal employee dictionary (Coresignal data dictionary, September 2026). If your outbound needs a dial, Coresignal alone will not give you one.

Coresignal's MCP email lookup also excludes employees in the EEA and UK (Coresignal MCP docs, September 2026). If your list is European, test that first.

API and developer experience

Both are REST APIs with a hosted MCP server. Seamless.AI makes you start a research job and poll for it. Coresignal separates search from collect, so you find IDs for free and pay when you fetch the record.

Seamless.AI takes the key in a Token header. You post a contact and get an HTTP 202 with requestIds (Seamless.AI docs, September 2026):

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 requestIds, or take the result by webhook. The docs do not say whether a missing record is charged, and they give no completion time for a job.

Coresignal takes the key in an apikey header. The collect call takes a profile shorthand name and costs 20 credits on the multi-source API (Coresignal docs, September 2026):

curl -X GET \
  "https://api.coresignal.com/cdapi/v2/employee_multi_source/collect/jane-doe" \
  -H "accept: application/json" \
  -H "apikey: $CORESIGNAL_API_KEY"

Search by filter is free and returns IDs. A search preview costs 10 credits for Base records and 20 for Multi-source, for up to 20 results a call (Coresignal docs, September 2026).

Rate limits point in opposite directions. Seamless.AI allows 60 requests a minute per endpoint for the whole organization, but one request takes up to 500 records. Coresignal ties speed to the plan: 10 requests a second on Pro, 50 on Premium, 100 on Scale.

On MCP, Seamless.AI offers 57 tools. Its search tools use no credits and its research tools do. Coresignal has 5 tools. entity_search costs 20 credits a call, entity_fetch costs 20 credits per employee or company record, and entity_fields and artifact_read are free. The email lookup tool bills 20 credits per email found in the server's own tool text, matching the 20-credit contact enrichment price. The MCP docs page still says 10, so we use 20 (Coresignal pricing, September 2026).

Pricing

Coresignal prints eight plans in dollars. Seamless.AI prints credits and no dollars. Credits are the one unit you can set side by side, and a credit buys roughly one contact at Seamless.AI against 10 to 20 credits per record at Coresignal.

At 10,000 records a month

For Seamless.AI, 10,000 contacts is 10,000 credits, with email and phone included. A Pro license carries 10,000 credits a month, so that is one license. If each record first comes from a search at 1 credit per 10 results, add 1,000 credits and you need two (Seamless.AI credit docs, September 2026). It publishes no license price, so there is no dollar figure here.

For Coresignal, take 10,000 work-email lookups at 20 credits each. That is 200,000 credits. Pro holds 35,000 and Growth 150,000, so the first plan that fits is Premium. It lists at $1,500 a month for 1,000,000 credits, or $1,350 a month billed yearly, which is $16,200 a year (Coresignal pricing, September 2026). Premium carries a 3-month rollover. The pricing page also flags Premium as contact-sales, so confirm you can buy it without a sales call.

Base records are cheaper but carry no email. 10,000 Base records at 10 credits is 100,000 credits, which fits Growth at $1,000 a month, or $900 billed yearly.

At 1M records a month

Neither vendor has a public 1M price. We do not multiply a rate out to 1M and call it a price.

For Seamless.AI, 1,000,000 research credits is 100 Pro licenses at 10,000 credits each. Add a search first and it is 1,100,000 credits, or 110 licenses. Both routes, and the bulk credit pool, are quote only (Seamless.AI docs, September 2026; bulk credits). Request time is short: at 500 records a call and 60 calls a minute, 1M records is 2,000 research calls, about 34 minutes of request windows. Job completion time is not documented.

For Coresignal, 1,000,000 work-email lookups is 20,000,000 credits. No public plan reaches that. The largest, Elite, is $5,000 a month for 10,000,000 credits, or $4,500 a month billed yearly, and covers 500,000 lookups (Coresignal pricing, September 2026).

Buying two Elite plans in one month is not documented, so the other 500,000 lookups have no public price. 1,000,000 Base records is 10,000,000 credits, which fits inside Elite, but Base records list no email. Elite is also flagged as contact-sales on the pricing page.

Bulk Collect takes 10,000 records a request, so 1M records is 100 requests.

Where Seamless.AI wins

• Phones. One credit covers email and phone together. Coresignal lists no phone field.
• Published contact counts. It states totals for emails and mobiles. Coresignal states neither.
• A rep app. It ships a Chrome extension, a dialer and buyer intent. Coresignal is data only (Seamless.AI, September 2026).
• A free license. 50 credits, no refill, to test with. Coresignal's trial is 2,000 credits for 7 days.

Where Coresignal wins

• A price you can read. Eight plans, from $49 a month, with credits printed on each.
• Job postings and signals. 482M+ job postings at 1 credit each, and daily company updates.
• Search is free. Filter or Elasticsearch DSL search returns IDs at no charge.
• Faster API on higher plans. 100 requests a second on Scale, against 60 a minute at Seamless.AI.
• Bulk and datasets. Bulk Collect takes 10,000 records a request, and flat files start at $1,000 a month.
• Easier exit. Seamless.AI subscriptions are annual and need 60 days' notice before renewal (Seamless.AI terms, September 2026). Coresignal sells monthly plans.

If you need volume through an API

We build LeadOcean, so weigh this section accordingly. It holds 693M people and 63M companies, reachable over REST and an MCP server with 12 tools. Free is 1,000 records, one-off, with no card. Pro is $499 a month, flat, with no credits and a limit of 100 requests per second per key (LeadOcean pricing, September 2026).

For bulk work, POST /v1/exports returns up to 50,000 rows per request. The app has an Exports page with a filter builder and CSV download (LeadOcean exports docs, September 2026). There is no sequencer, dialer or Chrome extension. If your reps live in Seamless.AI, or you need job postings, keep the tool you have.

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