The B2B Data APIs Worth Building On (2026)

Why we wrote this (and our conflict of interest)

Almost every 'best B2B data provider' list compares dashboards — seats, Chrome extensions, CRM sync. This post compares APIs: the layer you call from code, from a workflow tool, or from an agent.

The buying criteria are completely different. A per-seat price is meaningless when there are no seats. What matters instead is coverage you can actually take delivery of, freshness, latency, and whether the pricing model survives an agent that calls you forty thousand times a day.

Disclosure, up front: we build gtm.dev, which appears first on this list. We put it there because the post is about API-first GTM data and that is exactly what it is — but you should discount our opinion of our own product accordingly. We've tried to earn that back by being specific about what it doesn't do yet, which is the part vendors normally leave out.

Everything else here is a product we've evaluated, used in production, or lost a bake-off to. Where a vendor publishes pricing, we quote it. Where they don't, we say so rather than repeat a number from a review site. Verified July 2026.

What actually changed in this category

Three things happened that should change how you evaluate vendors.

Proxycurl died. Its homepage now reads 'Proxycurl is no longer in service' and pushes visitors to NinjaPear, a different product from the same founder. It was one of the most widely used LinkedIn-derived APIs in the space. Everyone who built on it spent a year migrating.

Clearbit stopped existing as a standalone API. It's HubSpot's Breeze Intelligence now — clearbit.com says 'Clearbit has joined HubSpot!' If you want Clearbit-style enrichment as an independent API, you're shopping in this list.

And consolidation is still running: Zoom announced a definitive agreement to acquire Common Room on 2 July 2026, expected to close within weeks. Terms weren't disclosed and Zoom's release makes no commitment to Common Room continuing standalone.

The pattern is the obvious one. This is a category where your vendor can disappear, get absorbed, or get repriced into somebody else's bundle. Build an abstraction layer over whichever provider you pick, and don't sign a three-year deal with a company that just agreed to be acquired.

The five things that actually differentiate these APIs

Everything else is noise.

• Deliverable coverage, not headline coverage. Every vendor quotes a big number that includes profiles it can crawl on demand, not profiles it holds. Ask instead: how many records will you ship me in a flat file today? The gap is routinely 4–5×.
• Cached vs live. A cached record answers in milliseconds and may be a month old. A live-fetched record is current and takes seconds. Neither is better — but don't pay the live premium for a nightly batch job, and don't put a live endpoint in a user-facing request path.
• API ergonomics. Batch endpoints, webhooks, sane pagination, structured errors. The single best tell: is resolution free? If turning 'acme.io' into a canonical company ID costs credits, you'll burn a meaningful share of your budget on plumbing.
• Agent-native surface. An MCP server, typed tools, and credits reported per call. If you're building agents, this is the difference between pointing at an endpoint and maintaining a wrapper library forever.
• Pricing model, including expiry. Per-credit, per-seat, or annual contract — and do the credits expire? Several vendors here expire them in six months, which quietly converts a credit pack into a subscription.

gtm.dev — signals and resolution, MCP-first

Ours. Read accordingly.

gtm.dev is the data layer underneath RocketSDR, exposed directly: around twenty tools over MCP with a REST mirror. Company and people data, plus the signal layer that's usually the actual reason you're buying — who's advertising, who's hiring, who just raised, what tech a company runs — along with TAM sizing, and concept search and lookalikes that run on embeddings rather than keyword matching.

Pricing is usage-based credits with no seats and no platform fee: resolution is 0.1 credit, search and enrich are 1 credit, signals are 1 credit, research is 5 credits. Test mode is free forever and you get 1,000 live credits without a card.

What it doesn't do yet, plainly: we haven't published a dollar-per-credit rate, so you can't model your bill from the website alone. And email and phone finding appear on our own pricing table as a tool class but are not shipped — if contact details are what you need today, buy one of the waterfall tools below instead.

Best for: teams building their own agent that need signals and entity resolution in the same place, and who'd rather call a tool than maintain a scraper.

Crustdata — live data and push-based signals

Crustdata trades Apollo's all-in-one workspace for an API-first data layer you build on. Rather than a dashboard with a sequencer attached, it serves company and people data plus real-time signals through a REST API, bulk flat files, and an MCP server. YC F24, $6M seed in late 2025.

The endpoint surface is genuinely broad: company search, enrich and identify; person search, enrich and contact enrich; job search; web search; social posts. Best for teams feeding their own AI SDR, CRM, warehouse or agents, and willing to give up point-and-click for data they control.

The standout is the Watcher API — webhook subscriptions on custom criteria like headcount rising a set percentage, the first hire into a department, a funding event, or job posts matching a keyword. Most of this category makes you poll for changes. Crustdata pushes them to you. Their social-post and post-reactor data is also rare in this category.

Credit costs are published and sensibly shaped: search is 0.03 credits per result, company enrichment 2–4 credits, person enrichment 1–7 depending on which contact fields you request, and identify and autocomplete are free. Credits expire after six months.

Two things to go in knowing. Crustdata quotes a $95/month starting price with custom enterprise plans, but its public pricing page lists no figures and routes to a demo — so treat that as vendor-quoted rather than published. And on coverage, it markets 1B+ people and 60M+ companies while its own dataset pages list 250M+ people and 12M+ companies. Both numbers are real; the larger one describes what it can reach with a live crawl, the smaller one what it will hand you today. Ask which one applies to your use case.

Best for: teams that want current data rather than a monthly snapshot, and especially teams that want to be told when something changes instead of asking.

Coresignal — the most transparent self-serve ladder

Coresignal is the provider we point people to first when they want to start without talking to anyone, because it's the rare vendor in this category that publishes an actual price list.

API plans: Free at $0 with 200 collect and 400 search credits valid for seven days, no card. Starter at $49/month for at least 250 collect and 500 search credits. Pro at $800/month for at least 10,000 collect and 20,000 search credits. Premium at $1,500/month for 50,000 collect and 150,000 search credits, adding webhooks and historical headcount. Yearly billing takes 20% off.

Flat-file datasets are sales-gated and start around $1,000: 70M+ companies, 895M+ employee records, 468M+ job records.

The historical headcount API is the underrated piece — genuine time-series rather than the growth percentages most competitors return, which matters if you're modelling trajectory rather than just filtering on it.

Best for: engineering teams that want to prototype this week without a sales call, and analytics teams that want the bulk dataset.

People Data Labs — the incumbent dataset

PDL is the long-standing default for person and company data at scale, and it's still the one most often embedded in other products — a lot of tools you already use are quietly PDL underneath.

It's strong on identity resolution and on being a stable, well-documented vendor, which sounds boring until you read the section above about vendors disappearing.

One honest note on our own research: PDL's pricing page renders client-side and did not expose plan figures to us, so we're not going to quote numbers we couldn't read. They do operate a free tier and self-serve plans alongside enterprise contracts — confirm current rates directly rather than trusting any list, including this one.

Best for: teams that want a large, stable, well-documented person dataset and are less concerned with real-time freshness.

Apollo — cheap data, but the API is gated

Apollo is the price leader on contact data and the default first stop for most teams, at $49–119 per seat per month for a 260M+ contact database.

The part that catches developers out: per Apollo's own pricing page, API access is available on Custom plans only. The self-serve tiers you see advertised are seat licences for the web app, not API credentials. Their fair-use policy also caps paying accounts at the lesser of dollars-paid divided by $0.025, or one million credits per account per year.

So Apollo is excellent value if you want a UI and acceptable value if you want an API — but you'll be in a sales conversation to get one, which undercuts the self-serve appeal that made it popular.

Best for: teams that want the cheapest broad contact database and are buying the app, not the API. We've written separately on where teams outgrow Apollo.

Bright Data — infrastructure, not a curated dataset

Bright Data sells at a different layer: proxies, scraping infrastructure, and a large dataset marketplace rather than an opinionated GTM product.

Dataset pricing starts at $2.50 per 1,000 records in JSON, CSV or Parquet, with tiers from 100K records up to a complete 3TB dataset, and discounts scaling with refresh frequency — up to 80% off for monthly refresh versus one-time. The marketplace covers professional profiles, company information, job listings, Crunchbase, PitchBook, Glassdoor and Google Maps.

The trade-off is real: you're buying raw material, not a resolved graph. There's no entity resolution, no signal layer, no opinion about what matters. If you have data engineers and want to build exactly what you want, that's a feature. If you want to call one endpoint and get an answer, it's a project.

Best for: teams with engineering capacity that want maximum control and the lowest cost per raw record.

TheirStack — hiring and technographic signals, priced sanely

TheirStack does one thing — job postings and the technographics you can derive from them — and it's the best value per credit in this comparison.

API plans run from a free 200 credits per month, then $59/month for 1,500 credits, $100 for 5,000, $169 for 10,000, $240 for 20,000, $400 for 50,000, and up to $1,500/month for a million credits. That's $0.0393 per credit at the entry tier falling to $0.0015 at the top. One credit per job, three per company lookup.

Job postings are the most underrated signal in outbound. A company hiring six Salesforce admins is telling you about a migration nobody has announced. Postings are public, dated, and specific, which makes them unusually honest as intent data compared to most of what gets sold under that label.

Best for: anyone building hiring-based or tech-stack-based triggers who doesn't want to pay intent-data prices.

Exa — web search built for agents

Exa isn't a B2B database and doesn't pretend to be. It's a search and retrieval API designed for agents, and it belongs here because it's how you cover the long tail no structured dataset reaches.

Pricing is unusually legible: $20 in credits at signup plus $10 monthly, search at $7 per 1,000 requests, page contents at $1 per 1,000 pages per content type, deep search at $12–15 per 1,000, and monitors at $15 per 1,000. Agent runs are $0.012–$1.00 depending on effort. They also resell enrichment at $0.02 per email and $0.07 per phone number.

When a structured provider returns nothing — a company too small, too new, or too foreign to be indexed — a web search plus an extraction pass usually still gets you an answer. That fallback path is worth building.

Best for: filling gaps in structured coverage, and any research step where the answer lives in a press release rather than a database field.

The contact-detail layer: LeadMagic, Hunter, and the waterfall tools

Finding a verified email or mobile is a genuinely separate problem from company and people data, and the economics are different: no single source exceeds roughly 40–60% coverage, so serious teams run a waterfall across several.

LeadMagic publishes clean credit pricing — $49/month for 2,000 credits up to $849/month for 100,000, at $0.0104–0.0204 per credit. Email finder is 1 credit, mobile 5, validation 0.25, job-change detection 3. Critically, credits only deduct on a successful result, which is the model you want.

Hunter runs $49/month for 2,000 credits, $149 for 10,000, $299 for 25,000, with a free tier of 50 credits and API access on all paid plans. It's the most established name here and the easiest to get approved through procurement.

For managed waterfalls across many providers at once, FullEnrich and BetterContact are the usual picks. We went deep on that whole layer — including quality benchmarks by region and the real cost of a bad number — in our B2B phone number provider comparison.

Best for: all of them are complements to, not substitutes for, the providers above.

The signal and visitor-ID layer

A separate category worth knowing about, since it often gets compared against the APIs above despite solving a different problem.

Common Room aggregates community, social and product signals and ships a first-party MCP server. Essential is $2,500/month billed annually for 5 seats and 100k contacts; higher tiers aren't published. Its contact data is professional-network-derived, phones come via a FullEnrich partnership, and its intent data is resold Bombora capped by tier. Note the caveat from earlier: Zoom announced its acquisition on 2 July 2026, so don't underwrite a multi-year contract this quarter.

The visitor-identification tools — RB2B, Vector, Warmly — all answer 'which companies, or people, visited my site' rather than 'tell me about this company.' They're worth having, but they're a different line item and they don't replace a data API.

Harmonic is the specialist for startup and funding data, popular with VC and with anyone selling to early-stage companies. Its pricing renders client-side and we couldn't read plan figures, so we're not quoting any.

The comparison, condensed

Self-serve means you can get a key today without a sales call. Prices are the published entry point as of July 2026.

• gtm.dev — signals + resolution, MCP-first. Self-serve: yes. 1,000 free credits, no card; dollar-per-credit not yet published. Best for agent builders who need 'why now' signals.
• Crustdata — live data + push signals. Self-serve: no, demo-gated. $95/mo vendor-quoted, credit costs published. Best for real-time and change detection.
• Coresignal — datasets + API. Self-serve: yes, free tier. $49 → $1,500/mo published. Best for starting today and for bulk.
• People Data Labs — large stable person dataset. Self-serve: yes. Pricing not readable on-page. Best for breadth and stability.
• Apollo — cheapest contact database. Self-serve: app yes, API no. $49–119/seat; API on Custom only. Best for the UI, not the API.
• Bright Data — raw scraping infra + marketplace. Self-serve: yes. From $2.50/1K records. Best for maximum control.
• TheirStack — hiring + technographics. Self-serve: yes, free tier. $59 → $1,500/mo. Best value per signal in the list.
• Exa — agent-native web search. Self-serve: yes. $7/1K searches. Best for long-tail gaps.
• LeadMagic / Hunter — contact details. Self-serve: yes. From $49/mo. Best as a waterfall component.
• Common Room — community + intent signals. Self-serve: no. $2,500/mo entry. Best held off until the Zoom deal settles.

Which one for your situation

Prototyping this week, no budget approval: Coresignal free tier, plus TheirStack free tier if you need hiring signals. Zero sales calls, working code same day.

Building an agent that needs to know why now: gtm.dev or Crustdata. Both are MCP-native. Pick us for signals plus resolution in one place, Crustdata for live fetch and webhook-based change detection.

You need to be told when something changes: Crustdata's Watcher API is the cleanest answer in this list. Coresignal Premium has webhooks too.

Analysis, scoring or modelling over a whole market: buy a flat file. Coresignal or Bright Data. APIs are the wrong shape and far more expensive for this.

You just need emails and phones: skip everything above and go to the waterfall tools. LeadMagic or Hunter to start, FullEnrich or BetterContact when coverage matters more than unit cost.

Maximum control, you have data engineers: Bright Data plus your own resolution layer. More work, lowest cost per record, no vendor lock-in.

Enterprise procurement, need one throat to choke: ZoomInfo. Expensive, deepest US coverage, and covered in our other comparisons.

The costs that don't appear on the pricing page

Three line items decide your real spend, and none of them are in the table.

Resolution overhead. If identifying an entity costs credits, you pay every time a name arrives messy — which is most of the time. Vendors that make identify and autocomplete free (Crustdata) or near-free (gtm.dev at 0.1 credit) are meaningfully cheaper in practice than their headline rates suggest.

Credit expiry. Six-month expiry, which several vendors here use, turns a credit pack into a subscription. Model your burn rate honestly before buying volume for a discount.

Misses you still pay for. Pay-per-lookup pricing charges you whether or not there's an answer. At a 50% hit rate that doubles your true cost per usable record. Pay-per-result pricing, which LeadMagic and BetterContact use, is worth a nominal premium.

And the largest one: migration. Proxycurl's users learned in 2025 that the cost of a data vendor includes the cost of leaving it. Write a thin internal interface over whichever provider you choose. It's an afternoon of work and it's the difference between a week of migration and a quarter.

Sources and methodology

Pricing was read from each vendor's own published pricing or documentation pages in July 2026 — Coresignal, TheirStack, Exa, LeadMagic, Hunter, Bright Data, Apollo and Crustdata's credit documentation. Where a page rendered client-side and exposed no figures, as with People Data Labs and Harmonic, we've said so instead of quoting a third-party estimate.

Proxycurl's shutdown and Clearbit's HubSpot acquisition were confirmed on their own homepages. The Zoom–Common Room agreement was confirmed from Zoom's newsroom, announced 2 July 2026 and pending close at the time of writing.

Crustdata's $95/month figure and its 1B people / 60M company coverage claim are vendor-provided; we've flagged both because neither appears on its public pricing page and its own dataset pages list smaller deliverable numbers.

We build gtm.dev and RocketSDR. We've included competitors we lose deals to, and recommended tools we have no relationship with where they're the better answer. If we've got something wrong — especially pricing — tell us and we'll correct it.

Frequently asked questions