In short
A B2B contact enrichment API takes a partial record — a name, a company, a domain, or a LinkedIn URL — and returns a verified business email and phone number you can actually use for sales and marketing. The seven providers below differ less on database size than on three things that decide your real cost: coverage (how often they return a usable match), verification (how often that match bounces or misdials), and pricing model (per-seat, credits, or pay-per-match).
For implementation, see the reverse email lookup API and its supported inputs.
TargetWise provides waterfall contact enrichment, company enrichment and reverse email lookup through REST, MCP and a workspace dashboard. Contact lookups use 15+ specialist sources and return available work emails and business phones. Returned phones are unclassified unless the response says otherwise; a returned email is not a deliverability guarantee. See the contact enrichment API.
You exported 1,000 prospects this morning. Your data tool returned verified work emails for about 580 of them and mobile numbers for fewer. The other 420 — the ones your reps need to contact today — came back blank, and you paid for several hundred of the lookups regardless of whether anything useful came out the other side.
That gap is the entire game in B2B contact enrichment. Every vendor in this category can show you an impressive headline number — "500M contacts," "1.7B records," "98% accuracy." What matters for sales and marketing is narrower and more stubborn: when you hand the API a real contact from your ideal customer profile, does it return a deliverable email and a phone number that connects — and what does each attempt cost you?
This guide covers seven providers focused on exactly that job: appending and verifying emails and phone numbers for outreach. We've deliberately left out the broader "platform intelligence" features (sequencers, dialers, intent scoring) except where they change the enrichment math, because that's not the decision you're making here. You're choosing a data layer.
What actually separates one enrichment API from another
Most comparison tables rank vendors by database size. That's the wrong primary axis. Two APIs can pull from the same underlying sources and return near-identical data at very different prices. The variables that change your outcomes are:
- Match rate (coverage). The percentage of your records that come back with a usable email or phone. This is ICP-dependent — a tool that's strong on US tech executives can be weak on EMEA mid-level roles.
- Verification depth. A returned email isn't a deliverable email. Single-source tools tend to return whatever they have; the strongest results come from real-time SMTP verification and multi-vendor cross-checks.
- Email vs. mobile. Mobile/cell numbers are the scarcest, most expensive, fastest-decaying field in the category. Many tools that are fine on email are weak on direct dials — and several charge a large credit premium for phone reveals.
- Delivery. Real-time API, bulk list/CSV enrichment, and a self-serve dashboard solve different problems. AI-agent workflows now add a fourth: an MCP server.
- Pricing model. Per-seat subscriptions, credit packs, and pay-per-match each create different incentives — and the model, not the sticker price, usually decides your cost per usable contact.
- Compliance. If you sell into the EU/UK, GDPR posture and where the data is sourced matter as much as coverage.
The 7 providers at a glance
| Provider | Core data focus | Mobile / phone | Delivery | Pricing model | |
|---|---|---|---|---|---|
| TargetWise | Contact and company enrichment | Available work email | Business phone, type unknown | REST · MCP · dashboard | Monthly usage balance |
| Lusha | Direct dials + emails (SMB/EMEA) | Yes | Strong dials | Extension · API (Pro+) · CSV | Per seat + credits |
| Apollo.io | All-in-one database + outreach | Yes | 8 credits ea. | Platform · API (Pro+) | Per seat + credits |
| Lead411 | US contacts + Bombora intent | Yes | Direct dials | Platform · API (top tier) | Per seat + export caps |
| ZoomInfo | Enterprise breadth + intent | Yes | Strong | Platform · Enrich API | Annual contract + credits |
| SalesIntel | Human-verified contacts (US) | Verified | Verified mobiles | Platform · API (Enterprise) | Quote-based, unlimited model |
| Seamless.AI | Real-time web search engine | Variable | Variable | Platform · extension · API | Credits, sales-led |
The order below follows the buyer's logic this guide is built around — pricing model and data focus first, brand size last. Read each as "what it's genuinely good at" and "what to pressure-test," not as a leaderboard.
Targetwise
pay-per-match · API-nativeThe pay-per-match data layer for teams that already own their CRM and sequencer.
Core is $49/month, with $0.15 per returned work email and $0.25 per returned business phone deducted from that included balance; Growth is $149/month, with $0.12 per returned work email and $0.20 per returned business phone deducted from that included balance; Scale is $399/month, with $0.09 per returned work email and $0.16 per returned business phone deducted from that included balance. Free includes 20 emails and 5 business phones. Unused balance resets at renewal. Subscriptions renew monthly until cancelled; unresolved requested fields consume no usage balance. See current pricing and subscription terms.
- Best forTeams who want a clean data layer they pay for by result, and developers wiring enrichment into a CRM, pipeline, or AI agent.
- CoverageMulti-vendor waterfall designed to lift match rate above any single source; business contacts only (no personal Gmail/Yahoo addresses).
- DeliveryREST API and an MCP server (single
enrich_contacttool for AI agents), plus bulk list enrichment and an account dashboard. - Monthly subscription; unused balance resets at renewal
For the architecture behind multi-vendor cascades, see our explainer on B2B email and mobile enrichment for AI agents, and the practitioner walk-through in Apollo.io alternatives that charge per match, not per seat.
Lusha
direct dials · SMB & EMEAThe phone-first lookup tool for SMB and EMEA prospecting.
Lusha built its reputation on one thing: direct dials that connect, surfaced fast through a Chrome extension on LinkedIn and your CRM. It's a genuinely strong pick for SMB sales teams and for EMEA coverage, and its compliance posture is enterprise-grade — GDPR, CCPA, SOC 2 Type II, and ISO 27701 are available on every tier, including free.
- Best forSDRs who prospect by phone, smaller teams, and EMEA-heavy outreach.
- Coverage100M+ profiles. Strong on direct dials; email accuracy is decent but coverage can be patchy — one independent mid-market test returned emails for roughly a third of lookups.
- DeliveryExtension and CSV enrichment on most plans; full API access from the Pro tier up.
- PricingPer-seat plus credits. Phone reveals are credit-heavy (reported at 10 credits each in 2026), and credits can expire — model your phone-to-email ratio before committing.
Apollo.io
all-in-one database + outreachData, sequencing, and a dialer in one affordable login.
Apollo is the most popular all-in-one: a 275M+ contact database (per Apollo, 2026) bundled with sequences, a dialer, and enrichment. For a small team that wants prospecting, outreach, and data under one login at a low entry price, the value is hard to beat. As of December 2025, waterfall enrichment is the default on its enrichment endpoints — Apollo now cascades to third-party sources when its own record is incomplete, which narrows the historical coverage gap.
- Best forStartups and small SDR teams that want data plus a sequencer and dialer in one tool.
- CoverageLarge database; independent tests put real-world email accuracy around 65–85% and phone accuracy lower (~55%), so verify before high-volume sends.
- DeliveryPlatform plus a well-documented API (including bulk people enrichment and waterfall flags) — API access starts on the Professional plan.
- PricingPer-seat plus credits, billed annually. Phone numbers cost 8 credits each, so phone-heavy programs burn credits ~8× faster than email.
Stop paying for the contacts you don't find
For this workflow, use the current TargetWise plan rates and usage calculator. Paid plans renew monthly; unused balance resets at renewal.
Lead411
US contacts + intentUS contacts plus Bombora intent, with unlimited exports on the right plan.
Lead411 pairs verified US contact data with Bombora buyer-intent at a mid-market price, and offers unlimited contact exports on some plans — a real differentiator for high-volume list building. It markets "double-verified" direct dials and triple-verified emails, and an enrichment API plus MCP server are available on higher tiers.
- Best forUS-focused mid-market teams that want intent signals and direct dials without ZoomInfo pricing.
- Coverage450M+ contacts, US-centric with thinner international coverage; email accuracy commonly cited around 80–85%.
- DeliveryPlatform and Chrome extension; lead-enrichment API and unlimited exports gated to the top tier.
- PricingPer-seat with export caps on entry plans (the cap is the catch — high-volume teams blow through it fast). Pricing was rebranded in late 2025, so published numbers vary by source.
ZoomInfo
enterprise incumbentMaximum enterprise breadth — if you can absorb the contract.
ZoomInfo is the enterprise standard for raw breadth. It cites 500M+ contacts and 100M+ companies, with one of the strongest direct-dial and verified-mobile footprints in the market (135M+ numbers). Its Enrich API (and Scaling APIs for big batch jobs) plug verified data into a CRM or warehouse, and in supported workflows it can even run its own multi-source waterfall.
- Best forEnterprise GTM teams with the budget and volume to justify a platform, not just a data feed.
- CoverageThe broadest in the category; email accuracy commonly estimated ~85%, with strong phone coverage. Note it appends emails but doesn't always validate deliverability — budget for verification.
- DeliveryPlatform plus real-time and bulk Enrich APIs and webhooks; data orchestration across 60+ vendors.
- PricingAnnual contracts only, typically starting around $15,000/yr and rising with seats, intent, and add-ons. Enrichment-relevant APIs are often a separate line item.
For a budget-led view of the incumbents and what they really cost, see our breakdown of what B2B data providers actually charge and the phone-data accuracy comparison.
SalesIntel
human-verified accuracyHuman-verified accuracy with mobiles included — US-focused.
SalesIntel's bet is human verification: researchers verify contact records and re-verify on a 90-day cycle, supporting a ~95% accuracy claim and a Research-on-Demand service that sources contacts not yet in the database (typically within 24–48 hours). It includes work-mobile numbers in the core plan rather than charging extra, which matters for cold callers.
- Best forMid-market to enterprise US teams that prioritize accuracy and verified mobiles over database size.
- Coverage100M+ contacts and 54M+ verified mobiles; strongest on US data, thinner internationally. Human verification means a slower refresh than scraped sources.
- DeliveryPlatform, RevDriver extension, and CRM enrichment; API access is gated to the Enterprise tier.
- PricingQuote-based, "unlimited" model (with a ~3,000 reveal/user/month cap in the fine print); median contracts reported in the mid-five figures.
Seamless.AI
real-time search engineReal-time and high-volume on a budget — bring your own verification.
Seamless.AI positions itself as a real-time search engine for contacts, crawling the web at query time rather than serving only stored records, with one of the largest database claims in the category (1.3B+ contacts) and a flat 1-credit-per-contact model that makes phone-heavy prospecting cheaper per reveal than credit-premium competitors.
- Best forBudget-conscious US SMB teams running high-volume outbound who will layer their own verification.
- CoverageLarge and fresh in theory; in practice independent tests put email accuracy around 74–85% and phone closer to 45–60%, with documented 20–30% bounce rates.
- DeliveryPlatform, Chrome extension, and API; SOC 2 Type II, GDPR and CCPA compliant.
- PricingFree tier then sales-led paid plans with no public Pro/Enterprise pricing.
How to choose: five questions
- Email-led or phone-led? Phone is the expensive, scarce field. If you live on the dialer, weight your choice toward verified-mobile strength (Lusha, SalesIntel, ZoomInfo) or a waterfall that cross-checks mobiles — and watch per-phone credit costs.
- Which model fits your volume? Spiky or list-based work suits pay-per-match or unlimited-export models; steady per-rep lookups suit seats; large batch refreshes suit credit packs or bulk APIs.
- Where's your ICP? US-centric tools (Lead411, SalesIntel, Seamless.AI) thin out in EMEA/APAC. For Europe, prioritize GDPR-grade sourcing and EMEA coverage.
- Did you test on your own data? Headline accuracy is marketing. Run 100–300 of your real contacts through any shortlist and measure deliverable emails and connecting numbers before you sign anything.
Get verified email + mobile — your way
Enrich a list in bulk, wire up the REST API or MCP server for real-time and agent workflows, or run lookups from your dashboard. Same multi-vendor waterfall, same pay-per-match pricing.
Frequently asked questions
What is a B2B contact enrichment API?
It's a programmatic interface that takes a partial record — a name, company, domain, email, or LinkedIn URL — and returns verified contact fields, primarily a business email and phone number, along with title and firmographic data. Sales and marketing teams use it to fill CRM gaps, enrich leads at the point of capture, and refresh decaying records automatically instead of researching contacts by hand.
For implementation, see the company enrichment API and its supported inputs.
Which contact enrichment API has the best email and phone coverage?
TargetWise provides waterfall contact enrichment, company enrichment and reverse email lookup through REST, MCP and a workspace dashboard. Contact lookups use 15+ specialist sources and return available work emails and business phones. Returned phones are unclassified unless the response says otherwise; a returned email is not a deliverability guarantee. See the contact enrichment API.
How accurate is B2B contact enrichment data?
Vendors advertise 95–98%, but independent testing usually finds real-world deliverable-email rates of roughly 75–90%, and phone/mobile accuracy materially lower — often 45–70% depending on the source. Accuracy also decays fast: B2B data goes stale at roughly 2–2.5% per month as people change jobs. Treat any headline number as a ceiling, verify before high-volume sends, and re-enrich active records at point of use.
What's the difference between pay-per-match and credit-based pricing?
With credit-based or per-seat pricing you generally pay for the lookup or export whether or not the returned data is usable, and unused credits often expire. With pay-per-match, you're charged only when the API returns a verified result — misses are free. For lists with meaningful coverage gaps, pay-per-match usually produces a lower cost per usable contact because you're not funding the blanks.
What is waterfall enrichment and why does it improve match rates?
Waterfall enrichment queries multiple data providers in sequence — Provider A, then B, then C — and returns the first verified result for each field, merging the best data point per field across sources. Because no single database covers everyone, cascading across 20+ vendors lifts coverage above any one source's ceiling and reduces bounces when paired with real-time verification. It's why multi-vendor tools consistently outperform single-source ones on a mixed B2B list. Our guide to enrichment for AI agents covers the architecture in depth.
Do enrichment APIs provide mobile and cell phone numbers?
Most do, but mobile is the scarcest and most expensive field, so treat it as a separate evaluation from email. Lusha, SalesIntel, and ZoomInfo are known for verified mobiles; several tools charge a steep credit premium for phone reveals (Apollo at 8 credits each, Lusha at 10). Waterfall and pay-per-match models cross-check phone data across vendors and charge only on a confirmed match, which avoids paying for numbers that don't connect.
Are B2B contact enrichment APIs GDPR compliant?
Compliance posture varies and matters most if you sell into the EU/UK. Lusha carries GDPR, CCPA, SOC 2 Type II, and ISO 27701 across all tiers; ZoomInfo, SalesIntel, Seamless.AI, and Targetwise publish their own compliance and sourcing positions. Compliant data sourcing is only half the picture — your own outreach and retention practices must also be lawful. Always confirm where a vendor sources data and review its data-processing terms before integrating.
How much does a B2B contact enrichment API cost in 2026?
It spans a wide range. All-in-one tools like Apollo start around $49–$119/user/month (annual); Lusha runs per-seat plus credits; Lead411 sits in the mid-market with export caps. Enterprise platforms (ZoomInfo, SalesIntel) are quote-based annual contracts, often $15,000–$100,000+/year. Pay-per-match data layers price by verified result rather than seat or subscription. Pricing in this category changes frequently and several vendors hide it behind a sales call — always confirm current numbers and what counts as a billable event. See our roundup of what B2B providers actually charge.
ZoomInfo vs. Apollo vs. a pay-per-match data layer — which should I pick?
For this workflow, use the current TargetWise plan rates and usage calculator. Paid plans renew monthly; unused balance resets at renewal.