TL;DR
- Apollo.io is a practical first test when sales teams want a contact database and operating workflow alongside the API. Its current documentation exposes endpoint credits and team-level rate limits. People enrichment costs one to nine credits under ordinary settings, while an email or phone waterfall can cost more; organization search costs one credit per page.
- People Data Labs is built for teams treating person and company data as an input to their own system. Person Pro starts at $98 monthly for at least 350 records; person and company search charge per returned profile, while ordinary enrichment charges on a successful match. Its Identify endpoint has different billing, so the endpoint matters.
- ZoomInfo is a sales-led API purchase most worth examining when the team already has a platform contract. Price the actual search, enrichment, export and storage rights in the written quote. There is no credible universal public API unit price to plug into a generic table.
- Coresignal suits market mapping and structured professional data at volume. It lists monthly API tiers from $49 Mini to $1,000 Growth before larger plans. Standard search/filter requests are free, but previews, agentic search and collected records have separate credit costs.
- LeadMagic gives developers an API-first contact-enrichment path. Its current entry plan is $99 monthly with 5,000 credits, not the $49.99 price in the old article. On that tier, search API requests cost a credit, while upper plans offer unmetered search under fair use; contact details still consume credits.
- Pick the vendor only after you define the operation and count accepted results, not calls or records displayed. Discovery, enrichment, verification, storage and customer-facing use are different purchases.
Start with the operation, not the vendor
“B2B data API” can describe at least three jobs. Discovery starts with filters, sector, employee count, country, technology, job title, and returns companies or people your team did not know. Enrichment starts with an identifier you already possess, such as a domain, person ID or name plus employer, and adds fields. Verification checks a known email or phone without necessarily finding a new contact. A vendor may offer all three, but one endpoint's rate limit, billable unit and license do not automatically apply to another.
Write an example request and acceptance rule before comparing prices. A discovery brief could be: “Find VP Sales and Revenue Operations leaders at US software firms with 100–1,000 employees, return a current employer, profile identifier and verified work email, and let us export accepted contacts to our CRM.” An enrichment brief could be: “Given 10,000 existing CRM records with name and domain, fill missing employer, title and email without overwriting a newer verified field.” Those jobs create different costs and different failure states.
Count the result the business can use. A person-search response may have 100 records but only 40 in the target geography, 25 at the right seniority and 15 with an exportable work email. If the purchase is for outreach, 15 is the relevant numerator. For account research, a company record without an email may still be useful. State which outcome qualifies before a vendor demo so a large raw database count cannot win by changing the denominator.
The last question is permission: can the team store returned data in its warehouse, use it for internal prospecting, deliver work to clients or expose it through a customer-facing product? These rights can differ even when the same endpoint technically works. Put storage duration, redistribution, refresh obligations and deletion handling in the procurement checklist. A successful HTTP response is not a license.
The five APIs compared
The prices and units below come from vendor material checked on 27 September 2026. They are starting points, not interchangeable quotes. For a broader non-API buying decision, see our B2B data enrichment tools comparison.
| API | Relevant public entry | What gets billed | Buyer who should trial it first |
|---|---|---|---|
| Apollo.io | Self-serve sales plans with credits; confirm current checkout | By endpoint: person data, mobile, organization search pages and optional waterfall vary | Sales team wanting database search plus CRM/outreach workflow |
| People Data Labs | Person Pro from $98/month for 350+ records | Search per profile returned; ordinary enrichment per successful match | Engineer building a controlled data pipeline or product evaluation |
| ZoomInfo | Contract quote | Credits and rights depend on selected API and contract | Existing enterprise customer extending a licensed platform |
| Coresignal | Mini $49/2,500 credits; Starter $199/12,000; Pro $499/35,000; Growth $1,000/150,000 monthly | Search, preview, collection and enrichment have distinct units | Market-mapping team that can forecast record depth and volume |
| LeadMagic | Essential $99/month with 5,000 credits | API search on lower tiers; contact reveals and enrichment by result | API-first team filling specific missing fields |
For every row, ask for a real response with the fields you require. A vendor's person-search result may be only a pointer that needs a second paid call. A returned “email” may be a confidence label rather than a recently checked mailbox. A 200 status may indicate a technically successful request but a business-invalid match. The rest of this comparison follows the actual purchase boundary for each provider.
1. Apollo.io
Apollo combines a prospect database, enrichment API and sales workflow. That makes it different from a pure data feed: a sales team can search in the application, enrich selected contacts, push data to its CRM and use the same vendor in outreach. A developer can also call person and organization endpoints. The attraction is fewer handoffs; the risk is treating every API action as covered by a single generic credit price.
Apollo's current API credit guide says people enrichment is one to nine credits per person on current plans when qualifying data is found: one for demographics or email and an additional eight when a mobile is returned. Bulk people enrichment follows the same per-person rule for up to ten people per request. The page cautions that optional waterfall configurations can cost much more, its cited typical ranges are one to four credits for email and eight to 25 for phone, with some configurations higher or billable even on a miss. Test the configuration you intend to run rather than using the simplest endpoint row as a universal forecast.
Discovery has its own economics. Apollo documents organization search at one credit per page, with up to 100 results per page; organization enrichment costs one credit per organization. Its guide also says record-management endpoints generally cost zero credits. The old article's broad “search is free” framing is therefore wrong for an organization-search job. Ask whether the people-search route you need returns the contact fields you need or requires a separate reveal or enrichment action.
Rate limits are also more specific than a single requests-per-minute figure. Apollo's rate-limit page says limits apply per team, not per key or user, and per endpoint across minute, hour and day windows. Current paid-plan enrichment endpoints show up to 1,000 requests per minute on that page, while paid search endpoints show 200 per minute, 6,000 per hour and 50,000 per day. A legacy plan may differ; Apollo provides a usage endpoint and response headers to inspect the team's actual limits. More API keys will not multiply a shared team allowance.
Apollo is a good first trial when the sales team values a usable prospecting application as well as an integration. It is a weaker fit when the buyer needs predictable unlimited mobile enrichment or licensed raw data for a separate customer-facing product. Apollo's pricing and plan terms should be reviewed for seats, included credits, export rights and commercial-use boundaries, with the exact API consumption measured in a small run.
2. People Data Labs
People Data Labs is a data-first purchase. Its person and company APIs are designed to enrich known entities or search a professional index; the vendor separately offers a bulk data license. This suits an engineering team that wants to build its own matching, storage and activation layer. It is less useful to a rep seeking a built-in sequencer or browser prospecting experience.
PDL's account and credit documentation lists Person Pro from $98/month, starting at 350 monthly records, and Company Pro from $100/month, starting at 1,000. Free offers up to 100 monthly records with core fields. Do not assume the free tier contains every contact field needed to evaluate a paid outreach workflow; verify the field bundle before comparing match rates.
The billing split is clear for the common endpoints: ordinary person, company and IP enrichment use one credit per successful request, bulk enrichment up to one per match in the batch, while person and company search use one credit per profile returned. A broad search yielding 1,000 profiles can consume 1,000 credits even if an analyst later selects only 50. Tight filters and a small preview matter. However, not every PDL endpoint shares the success-only rule: its Person Identify FAQ says that operation can bill per request regardless of match. Ask for the exact endpoint list in the quote and measure response-status billing in a pilot.
PDL also describes a separate annual bulk data license for on-premise datasets. That can be more appropriate than millions of individual API calls when the buyer needs a large, refreshed corpus. The data license and a self-serve API subscription do not grant identical use rights by implication; review permitted uses and the Acceptable Data Use Policy in the actual agreement.
PDL is the strongest candidate here when the buyer has an engineering team and needs licensed person/company data as a component of a system it controls. It is less compelling for an exploratory search that returns many profiles the buyer will discard, or for a sales operation that needs workflow UI rather than an API. Test the exact fields and matching keys before committing to a large annual license.
3. ZoomInfo
ZoomInfo is an enterprise sales-intelligence platform with API access within a contract. Its value for this comparison is not a low public per-record price; it is the possibility of using a dataset and workflows a large sales organization may already own. A team with a current subscription should examine whether an API-based enrichment job is permitted under that contract before buying a second tool for the same field.
The vendor's API documentation site describes Search and Enrich functions, but the public pages available in this review did not provide a reliable universal API tariff, and the pricing route is sales-led. The old article asserts that search always costs zero credits and enrichment alone costs one; that may describe a particular legacy configuration, but it should not be generalized to every current agreement without the buyer's endpoint documentation and contract. Ask the account team to show the exact Search and Enrich units, what constitutes a redeemed record, and whether viewing the same record again consumes another unit.
Specify the data scope. A contact enrichment can return a broad profile, but the purchase might be driven by a narrower field such as a current title, direct dial or installed technology. The quote should cover seats, API access, geography, contact or company credits, export, warehouse storage, permitted client use, rate limits and renewals. If the team already has a contract, compare the incremental cost of API activation with buying an additional specialist provider. If it does not, compare the full platform cost rather than assuming a phone or email field has a standalone price.
For implementation, search or match a small set first, inspect identifiers, then enrich only records that meet the team’s criteria, subject to the actual endpoint billing rules. Do not overwrite a CRM's newer verified field with an older vendor value. Log source and retrieval time so a wrong match can be traced. A missing record, a rate-limited call and a permission error are different outcomes and should not be handled by the same retry loop.
ZoomInfo is a reasonable candidate for a contracted enterprise team that can use its broader dataset and support. It is a poor default recommendation for a small team asking for a transparent, self-serve API budget. No claim about universally superior US coverage or a five-figure minimum is needed to make that distinction.
4. Coresignal
Coresignal sells structured company, employee, job and contact data through APIs and datasets. Its pricing table publishes a useful monthly ladder: Mini $49 for 2,500 credits; Starter $199 for 12,000; Pro $499 for 35,000; Growth $1,000 for 150,000, before larger Premium, Scale and Elite tiers. Entitlements change across the ladder, including certain multi-source and Contact Enrichment endpoints, rate limits and rollover. A highlighted calculator card on the site appears to mix a Mini price with Growth-like features, so use the explicit plan comparison and confirm the selected SKU in checkout.
The credit documentation is the important counterweight to the headline “search is free.” Standard Elasticsearch DSL and filter search calls do not deduct credits. But Search Preview costs credits, ten for base/clean and 20 for multi-source, and agentic search uses a separate 20- or 100-credit base cost. Collecting a base or clean employee or company record costs ten credits; multi-source records cost 20; contact enrichment costs 20. A discovery process can therefore do many free filters yet still spend heavily when analysts preview, collect or enrich broad result sets.
The business decision is how much record depth is required. If a market map needs company names and headcount only, buying a 20-credit multi-source employee record for every candidate wastes budget. If account research needs work history, job events and richer profiles, the lower-cost base record may be incomplete. Request sample payloads for base, clean, multi-source and contact enrichment; choose the narrowest version that actually passes the acceptance test.
At the $49 Mini tier, 2,500 credits could theoretically pay for 250 ten-credit base records or 125 twenty-credit records, before previews or other calls. That arithmetic says nothing about whether the endpoint is included on Mini or whether the record contains the required fields. Growth's 150,000 credits could theoretically buy 7,500 twenty-credit records before other usage. The relevant cost is per accepted record in the exact tier that grants the desired API.
Coresignal fits an engineering or research team that can manage large result sets and distinguish search, preview and collection in its code. It fits less well when sellers need a finished prospecting UI or when the buyer assumes a free search returns a free usable contact. Its dataset licensing and permitted retention should be checked separately from a self-serve API plan.
5. LeadMagic
LeadMagic's current pricing page lists Essential $99/month with 5,000 credits, Growth $249 with 20,000, Professional $499 with 50,000 and Ultimate $849 with 100,000. Every current plan includes the enrichment API and a shared credit pool. The old article's Basic $49.99 entry is out of date and should not inform a 2026 budget.
The API can search people, companies and jobs, then reveal or enrich specific data. The pricing page distinguishes in-app search, which is included from Essential without search credits, from the Search API. On Essential and Growth, an API search request costs one credit. Professional and Ultimate include unmetered search API under fair-use and account-wide request-rate limits. A developer cannot assume that because manual search is free, an automated discovery pipeline is free on the entry tier.
Contact actions have their own schedule: one credit per successful email finder result, five per valid mobile, and separate rates for validation or other enrichment operations. LeadMagic says failed or empty result lookups do not deduct the corresponding result credits. A search request may still have cost on lower plans. The distinction matters when the list is sparse: model one credit for the search attempt, then add the cost of only the accepted fields returned. Reconcile the estimate with the usage log rather than trusting a plan's promotional cost-per-credit line.
LeadMagic is a good fit when a technical team knows the field it wants to fill and can trigger enrichment only for missing CRM values. It is less useful to a buyer who needs a complete account research application or assumes “unmetered search” allows database replication or customer-facing resale. Its page describes fair-use and internal-use restrictions for upper-tier search; get the right license if you serve outside users.
Model a 10,000-record job before buying
Take a real planning example: 10,000 CRM people with name and company domain. The team wants a current employer and work email for all, and mobiles for only 1,000 high-priority people. It is not a vendor performance benchmark; the quantities are inputs to a budget.
The implementation should first deduplicate people and suppress records that already have a recently verified field. Suppose that leaves 6,000 email gaps and 800 mobile gaps. An API that charges by returned field may cost much less than one that enriches all 10,000 indiscriminately. Apollo's standard person enrichment could use one credit when email/demographics are returned and up to nine with a mobile, but a configured waterfall can cost more. LeadMagic's posted field schedule suggests up to 6,000 email credits plus 4,000 mobile credits if every requested lookup succeeds, before lower-tier search requests. Coresignal's twenty-credit contact-enrichment unit could consume 120,000 credits for 6,000 returned enrichments, if that endpoint and field set are applicable. PDL's ordinary successful person enrichment would consume one credit per successful matched request, but its Person Pro entry allowance is far below 6,000. None of these numbers is a final invoice: failures, endpoint selection, plan scope and field eligibility change it.
Now change the denominator from matches to accepted updates. If 6,000 requests produce 4,000 matches but only 3,000 are current and safely mergeable, divide the total operation and subscription cost by 3,000. Record the 2,000 empty and 1,000 rejected outcomes, because billing may attach to a successful API match even when your business rejects the data. A “cheap credit” is not cheap if most results trigger manual conflict review or overwrite a better CRM value.
Rate limits affect labor and elapsed time too. At 200 requests a minute, 10,000 one-record calls have a theoretical minimum of 50 minutes before retries, batching, concurrency rules and hourly or daily windows. An endpoint with a 2,000-per-day cap would require at least five days for the same one-record sequence. Use the actual purchased account limits and batch endpoint rules; do not multiply API keys to evade a team-level cap. For a one-time 400,000-record build, request a bulk feed or a negotiated batch route instead of assuming the self-serve API is the only path.
A same-list API trial
Give each provider the same 300 existing people and 100 discovery filters or target companies drawn from the markets that matter. Include easy and difficult records: established and fast-growing companies, common and ambiguous names, two or more countries, recently changed jobs and already-known CRM contacts. Define the fields required for acceptance before seeing results.
For enrichment, send equivalent identifiers to the closest matching endpoint. Record request payload, response status, returned person and company IDs, field-level provenance or verification date where available, usage before and after, and whether the result was accepted. Check a sample independently for employer, title and email. For discovery, cap returned profiles per query so a broad PDL search or Coresignal collection cannot overwhelm the budget; then measure how many results fit the ICP and can be exported under the intended license.
Ask five operational questions of every vendor: What is charged on an empty result? What is charged when an API match is the wrong person? Does a search result include contact details, or is a second reveal needed? How long may data be stored and refreshed? Can the intended internal, client-service or embedded use be licensed? Add rate-limit headers and 429 behavior to the prototype. A 429 needs a controlled retry; an empty result usually does not.
The final comparison should show accepted results per input, cost per accepted result, time to complete the batch, fields absent by segment and rights needed to ship the integration. A sample of 400 inputs cannot prove a worldwide data-accuracy ranking, but it can expose an endpoint or contract that simply does not fit the buyer's job.
Which API should you choose?
Choose Apollo when sales users need one environment for search, enrichment and activation, and the team can monitor the particular endpoint and waterfall credits. Choose People Data Labs when data is going into a system you build and you want a clear per-profile search versus successful-enrichment model, with a separate bulk license available if volume warrants it.
Choose ZoomInfo if you already license the platform or need its wider contract scope and can negotiate the API and storage rights. Choose Coresignal when you need professional and company data at different depths, can control previews and collection, and can purchase the tier that actually contains the endpoint. Choose LeadMagic for a focused API-first reveal workflow with a shared credit pool, while budgeting lower-tier search API requests separately.
If the job is specifically finding work email from an existing professional profile, our profile-to-work-email API comparison narrows that choice. If you plan to call several sources only when the first misses, start with a measured waterfall enrichment workflow rather than paying all of them for every row.
The Clay Waterfall Enrichment Guide provides a practical sequence for qualified inputs, provider fallback and accepted enrichment output.
FAQ
What is the difference between a discovery API and an enrichment API?
Discovery takes filters and returns new candidate people or companies. Enrichment takes an identifier you already hold and adds or updates fields. Search may bill per page or returned profile; enrichment may bill per successful match or returned field. Check the exact endpoint and response, not just the product category.
Does Apollo charge one credit for every API call?
No. Its current guide lists zero-credit management endpoints, one-credit organization-search pages, one-credit organization enrichment and one-to-nine-credit standard people enrichment. Optional email and phone waterfalls can cost more, including some configurations that charge for misses. The workspace usage ledger confirms the actual bill.
Is People Data Labs search free if no contact is accepted?
Its documented person and company search charge per profile returned, not per contact your team later accepts. Ordinary enrichment is generally billed on successful matches, while Person Identify has different request-billing rules. Define the endpoint and cap search results during testing.
Is Coresignal search free?
Its standard search/filter endpoints are listed as free of credit charges. Preview, agentic search, collecting employee or company records and contact enrichment each have their own charges. A “free search” can still lead to an expensive list if the workflow collects every candidate.
Does LeadMagic include unlimited API search on its $99 plan?
No. Essential includes in-app search and the full enrichment API, but its Search API costs one credit per request. Professional and Ultimate list unmetered Search API under fair-use and rate controls. Email, mobile and other details retain their own credit schedule.
When should we buy a bulk data license instead of API calls?
When the job is a very large initial build or regular full-corpus refresh, rather than a small stream of known records. Compare the licensed dataset, refresh cadence, permitted storage and downstream use against the total API cost and elapsed time. PDL explicitly offers an annual bulk data license; other vendors may quote bulk delivery, but obtain the rights in writing.
