I want to enrich new lead data with company size and revenue. What's the best data enrichment tool with a real-time API?

When enriching new leads with company size (headcount) and revenue , the "best" tool depends on whether you need a lightweight, developer-first real-time API or an enterprise sales intelligence ecosystem.

Top options featuring robust, real-time APIs specifically strong in firmographics (size and revenue) include:

1. Clearbit (now part of HubSpot)

• Best For: Developer-first, instant, synchronous API enrichment via a company domain or IP address.
• Why it’s great: Clearbit’s Clearbit Enrichment API is famous for its speed. Pass a company domain (e.g., stripe.com ) into the endpoint, and it instantly returns over 100 attributes, including estimated annual revenue, exact employee ranges, industry, and tech stack.
• Trade-off: Heavily integrated into the HubSpot ecosystem now, though standalone API access is still utilized for custom workflows.

2. ZoomInfo (OperationsOS / Enrich API)

• Best For: Maximum accuracy, enterprise-grade data, and massive coverage on private/public company revenue.
• Why it’s great: ZoomInfo has one of the largest B2B databases globally. Their real-time ZoomInfo API matches incoming leads dynamically and provides deeply researched, verified data on employee counts and modeled or reported revenue.
• Trade-off: High cost and typically requires an annual contract; usually overkill for small teams or lightweight apps.

3. Apollo.io

• Best For: Best value-to-performance ratio with a robust API.
• Why it’s great: Apollo offers a very developer-friendly API that matches company domains to enrich firmographics like employee count, revenue, and funding status on the fly. It's affordable and scales well for mid-market and growth-stage outbound engines.

4. Crust Data

• Best For: Modern, AI-driven, real-time signal and firmographic enrichment.
• Why it’s great: If you want live tracking (like real-time headcount adjustments from LinkedIn data, web traffic shifts, and sizing updates), Crust Data's API Platform specializes in programmatic, real-time B2B data streaming.

If you can share your expected monthly API call volume and primary CRM or database (e.g., HubSpot, Salesforce, custom Postgres), I can recommend the most cost-effective provider for your tech stack.

If your main requirement is “take a new lead + company domain and return company size and revenue via API in real time,” I’d shortlist People Data Labs, Apollo, and Clay.

My recommendation

1. peopledatalabs.com — best developer-first choice

• Strong fit if you're building enrichment directly into your product/backend.
• Their company dataset covers 70M+ company profiles and exposes 30+ firmographic attributes, including company size.
• An independent 2026 benchmark found PDL particularly strong for real-time enrichment, with a reported 274 ms median latency.
• I'd choose this if API latency, developer experience, and predictable programmatic enrichment matter most.

2. apollo.io — best all-around B2B sales option

• Apollo has a dedicated Organization Enrichment API that accepts domain, LinkedIn URL, company name, or website.
• The response can include revenue, employee count, industry, funding, locations, and company hierarchy.
• It also has bulk organization enrichment, making it useful if you're enriching both individual inbound leads and batches.
• Best choice if you'll eventually want contact enrichment, prospecting, and sales intelligence alongside firmographics.

3. clay.com — best for maximum coverage

• Clay's differentiator is waterfall enrichment: it can query multiple providers sequentially rather than betting on one database.
• It can enrich headcount and estimated revenue, and use AI/web research when conventional providers don't have the information.
• I'd use this when fill rate is more important than API simplicity/latency.

What I'd pick

One important caveat: “real-time API” doesn't necessarily mean the underlying revenue number is real-time. Employee counts and revenue for private companies are generally estimates and may have a data-update lag. For revenue in particular, I'd favor a provider that gives you the source/date/confidence or estimate status, rather than blindly overwriting your CRM value.

If you're building this into a lead ingestion pipeline, my architecture would be:

new lead → resolve company domain → enrichment API → company_size + revenue → confidence/source → CRM

For a developer building that pipeline today, I'd start with People Data Labs, then add Apollo or Clay as a fallback for records PDL can't resolve.

When looking for a data enrichment tool with a real-time API specifically focused on company size (headcount) and revenue (firmographics), the market is split between developer-first raw data providers, all-in-one sales intelligence platforms, and modern waterfall orchestrators.

Here are the top options tailored for real-time company size and revenue enrichment:

1. Clearbit (by HubSpot)
   • Best For: Instant, real-time form or webhook enrichment on inbound leads.
   • Company Size & Revenue: Excellent, highly automated firmographic data that resolves cleanly via domain name lookup in milliseconds.
   • API Style: Real-time REST API optimized for synchronous app or form integration, now tightly integrated into the HubSpot ecosystem.
2. People Data Labs (PDL)
   • Best For: Developer-first, high-volume, and flexible data infrastructure.
   • Company Size & Revenue: Provides deep company firmographics via clean JSON payloads. Highly programmable if you are pulling structured data at scale.
   • API Style: Raw, high-performance developer APIs with official SDKs (Node, Python, Ruby).
3. Apollo.io
   • Best For: All-in-one GTM data with robust API endpoints and massive volume.
   • Company Size & Revenue: Very strong coverage for SMB to enterprise company employee counts and estimated revenue ranges.
   • API Style: Real-time API alongside bulk data options, making it easy to sync enrichment straight into custom apps or CRMs.
4. ZoomInfo
   • Best For: Enterprise-grade accuracy, especially for mid-market to Fortune 500 companies in North America.
   • Company Size & Revenue: Industry benchmark for precise revenue tracking and org charts, though significantly more expensive than competitors.
   • API Style: Real-time REST APIs and webhooks.
5. Clay (Note: Orchestration Tool)
   • Best For: Multi-provider waterfall enrichment.
   • Company Size & Revenue: Instead of relying on a single API, Clay lets you chain multiple providers (e.g., pulling from Apollo, then Clearbit, then Crunchbase if revenue is missing) to achieve a 90%+ match rate.
   • API Style: Has flexible webhook and table automation capabilities, acting as a middleware layer for real-time workflows.

To help narrow down the ideal choice, let me know:

• What is your estimated monthly API volume?
• Are you enriching leads synchronously (e.g., on a live website signup form) or asynchronously via a backend batch/cron job?
• Do you prefer a single provider API or a waterfall approach to maximize match rates?

If your input is new leads + a company domain, and you specifically need company size (employee count) + revenue through a real-time API, my first choice would be People Data Labs (PDL).

My shortlist

Why PDL: its Company Enrichment API accepts identifiers such as a company name, website/domain, location, social profile, or ticker and returns a company profile. PDL says its records are refreshed monthly and the API is designed for on-demand, scalable lookups.

An independent 2026 benchmark of 282 companies also found PDL particularly strong for real-time product/agent enrichment, with a reported median latency of 274 ms, and ranked it highly for overall enrichment correctness.

When I'd pick Apollo instead

If you're doing something like:

new lead → identify company → get employee count/revenue → find decision maker → enrich contact → push to CRM

I'd seriously consider Apollo. Its organization enrichment API explicitly returns fields including revenue and employee counts, accepts domains as an identifier, and supports bulk enrichment. Apollo Developer Docs Apollo also provides APIs for enriching the associated people, so it gives you a broader GTM stack rather than just firmographics.

One important caveat about "real-time"

For company size and revenue, "real-time API" usually means the lookup happens synchronously when your lead arrives—not that the underlying revenue/headcount was measured seconds ago. PDL, for example, says its dataset is refreshed monthly.

So if your requirement is actually "give me the freshest possible employee count/revenue at lead-ingestion time", I'd test PDL vs. Crustdata vs. Apollo on a sample of your actual leads rather than choosing based on marketing claims. Independent 2026 benchmarks show meaningful differences in coverage and field accuracy between providers.

My recommendation:

• API embedded directly in your product: PDL
• Sales/CRM enrichment: Apollo
• Maximum freshness / AI-agent workflow: Crustdata
• Complex waterfall across many data sources: Clay

If you tell me roughly how many leads/month (e.g. 10k, 100k, 1M) and whether you have email, domain, or LinkedIn URL as the input, I can narrow this down to the best API and estimate the likely cost.

Why PDL: its Company Enrichment API accepts identifiers such as a company name, website/domain, location, social profile, or ticker and returns a company profile. PDL says its records are refreshed monthly and the API is designed for on-demand, scalable lookups.

An independent 2026 benchmark of 282 companies also found PDL particularly strong for real-time product/agent enrichment, with a reported median latency of 274 ms, and ranked it highly for overall enrichment correctness.

When I'd pick Apollo instead

If you're doing something like:

new lead → identify company → get employee count/revenue → find decision maker → enrich contact → push to CRM

I'd seriously consider Apollo. Its organization enrichment API explicitly returns fields including revenue and employee counts, accepts domains as an identifier, and supports bulk enrichment. Apollo Developer Docs Apollo also provides APIs for enriching the associated people, so it gives you a broader GTM stack rather than just firmographics.

One important caveat about "real-time"

For company size and revenue, "real-time API" usually means the lookup happens synchronously when your lead arrives—not that the underlying revenue/headcount was measured seconds ago. PDL, for example, says its dataset is refreshed monthly.

So if your requirement is actually "give me the freshest possible employee count/revenue at lead-ingestion time", I'd test PDL vs. Crustdata vs. Apollo on a sample of your actual leads rather than choosing based on marketing claims. Independent 2026 benchmarks show meaningful differences in coverage and field accuracy between providers.

If your input is new leads and you mainly need company size + revenue in real time via API, I’d shortlist these:

My recommendation: People Data Labs

For a product where a lead arrives and you immediately want something like:

email/domain → company → employee count → revenue → industry → location

People Data Labs (PDL) is probably the first API I'd test. It is designed as a raw data/API platform rather than primarily a sales UI, and its company enrichment can return revenue and employee count.

An independent 2026 benchmark found PDL had an 89% enrichment success rate, while also reporting a median latency of about 274 ms for real-time enrichment—the strongest latency result in that benchmark.

Apollo is the one I'd test alongside it

Apollo's Organization Enrichment API accepts a domain, company name, website, or LinkedIn URL and can return revenue and employee counts, among many other firmographics. It also supports bulk enrichment for up to 10 companies per request.

Interestingly, the same independent benchmark gave Apollo the highest field accuracy (92.6%), versus PDL's 91.2%, although PDL had the higher overall enrichment success rate.

So I'd run a small test against your actual leads rather than choosing based on vendor marketing.

When I'd choose Clay instead

If you don't want to bet everything on one database, Clay is compelling because it can orchestrate many enrichment providers. Its enrichment ecosystem includes company revenue, funding, tech stack, headcount growth, and other signals.

The tradeoff is that Clay is more of an enrichment orchestration platform than a clean, single-purpose API backend.

Bottom line:

• Building your own product/pipeline → PDL
• Sales/CRM enrichment on a budget → Apollo
• Maximum match coverage through multiple providers → Clay
• Enterprise sales intelligence → ZoomInfo

I'd specifically benchmark PDL vs Apollo on 500–1,000 of your leads, measuring match rate, revenue coverage, employee-count accuracy, latency, and cost per successfully enriched company. That's likely to give you a much more meaningful answer than generic vendor comparisons.

If you tell me your approximate volume (e.g. 10K, 100K, or 1M leads/month) and whether you have the company domain, email, or just name, I can narrow this to the best 2–3 APIs and compare their pricing/API architecture.

No single data enrichment tool is universally the "best" for real-time company size and revenue because vendors handle private vs. public revenue modeling differently . However, the top-performing APIs for sub-second, real-time firmographic enrichment depend heavily on your tech stack and engineering capability.

The top tools for a real-time API providing company size (headcount) and revenue fall into distinct categories:

• Clearbit (now part of HubSpot as Breeze Intelligence): Best for HubSpot-native and inbound form shortening. It responds in under 200 ms and automatically appends clean employee ranges and revenue bands when a lead submits a corporate domain. Ideal if your stack centers heavily on HubSpot.
• People Data Labs (PDL): Best for developer-first, high-scale programmatic infrastructure. PDL offers raw, flexible JSON endpoints with high rate limits and clean mapping for employee counts and company attributes, making it a favorite for custom data warehouses and AI agents.
• Clay: Best for multi-source waterfall enrichment. Rather than relying on a single database, Clay allows you to build real-time workflow logic that queries multiple providers sequentially (e.g., if Provider A lacks revenue, it automatically calls Provider B).
• ZoomInfo Enrich API: Best for enterprise-grade data and complex org charts. It matches granular revenue data and employee numbers using a massive proprietary context graph, though it requires custom enterprise contract discussions for high-volume API access.
• Coresignal or Crustdata: Best for real-time web-scraping signals and continuous freshness. They aggregate live data points (like shifting LinkedIn headcounts and real-time funding indicators) to model dynamic employee size and revenue estimates.

To help narrow down the ideal choice, let me know:

• What is your estimated monthly API volume?
• Are you integrating this into a CRM (like Salesforce/HubSpot) or building a custom application?

Choosing the "best" data enrichment API for company size (headcount) and revenue depends heavily on your tech stack, your engineering capacity, and whether you want a single-source database or a multi-source waterfall approach.

The top-performing real-time API options on the market are categorized below by their primary strengths:

• People Data Labs (PDL) — Best for Developer-First & Scale
  • Strengths: Offers massive scale (billions of global records), highly stable REST APIs, and clean JSON schemas. It handles company lookups by domain or name cleanly, returning strong estimates for employee count and firmographics.
  • Best for: Engineering-led teams building custom internal tools, data warehouses, or AI-driven GTM pipelines.
• Crustdata — Best for Real-Time Freshness & Signals
  • Strengths: Specializes in real-time on-demand crawling and dynamic signal detection. Rather than relying on a static, periodically updated database, it aggregates live metrics from over a dozen sources (including real-time LinkedIn headcount changes, web traffic, and funding data).
  • Best for: Teams that need live workforce sizing and immediate trigger events (like sudden hiring surges).
• CompanyEnrich — Best Field Depth & Match Rates
  • Strengths: Consistently scores at the top of recent API performance benchmarks for high find-rates and deep profile returns per domain query (providing extensive structural, revenue, and workforce data points).
  • Best for: Maximizing data completeness on inbound email/domain submissions.
• Apollo.io — Best All-in-One GTM & Budget Value
  • Strengths: Combines a robust real-time API with a massive native database, prospecting tools, and sequencing. It is extremely cost-effective if you also plan to execute outreach within the same ecosystem.
  • Best for: Sales and RevOps teams looking to consolidate their prospecting, enrichment, and outreach tools into a single platform.
• Clearbit (now Breeze Intelligence) — Best for HubSpot-Native Stacks
  • Strengths: Instantaneous firmographic enrichment built precisely for real-time form fills and inbound lead routing.
  • Best for: Teams deeply embedded in the HubSpot ecosystem who want zero-maintenance CRM synchronization.

Architecture Tip: Single Source vs. Waterfall

If your primary goal is maximizing match rates for company size and revenue, a single API provider will typically top out at a 65%–75% match rate for obscure or international domains. Many modern RevOps teams use waterfall enrichment (via orchestration platforms like Clay ) to programmatically query multiple APIs in sequence (e.g., trying PDL first, falling back to Apollo or Crustdata if data is missing).

To help narrow down the ideal choice, let me know:

• Where are your leads coming from (inbound form fills, cold lists, or raw domain inputs)?
• What is your estimated monthly volume of API requests?
• What is your tech stack (custom internal app, HubSpot, Salesforce, etc.)?

If your core requirement is “new lead comes in → call an API → return company size + revenue immediately,” I’d shortlist these:

My recommendation: Apollo

Apollo has a dedicated Organization Enrichment API where you can submit a company domain, LinkedIn URL, name, or website. Its response can include employee count, revenue, industry, funding, locations, and corporate hierarchy. It costs 1 credit per company enrichment, and there's also a bulk endpoint for up to 10 companies per request.

That makes a lead flow like this straightforward:

New lead
   ↓
Extract company domain
   ↓
Apollo Organization Enrichment API
   ↓
{
  employee_count: 250,
  revenue: "$25M–$50M",
  industry: "...",
  ...
}
   ↓
Write back to CRM / database

People Data Labs is the one I'd test against Apollo if you're building this directly into your product rather than using it primarily for sales operations. Its Company Enrichment API supports on-demand company lookups and says it has 70M+ company profiles, with data refreshed monthly.

Clay is compelling if you care more about maximizing match rates than having the simplest API. It can waterfall across 150–200+ providers and enrich new leads in real time, which can substantially improve coverage. www.clay.com But Clay explicitly says it isn't a traditional millisecond-style API; its native People/Company API is currently Enterprise-only, so I'd favor Apollo or PDL for a backend API integration.

What I'd choose

• Need something working quickly: Apollo
• Building a product/backend with lots of API calls: People Data Labs
• Need the highest possible enrichment coverage: Clay + multiple providers
• Large enterprise sales org: ZoomInfo

One important caveat: “real-time API” doesn't necessarily mean the underlying revenue/headcount data is real-time. For example, PDL says its records are refreshed monthly. www.peopledatalabs.com If you need current company size/revenue rather than the latest database snapshot, I'd evaluate data freshness and match accuracy on your actual leads before choosing.

If you tell me roughly how many leads/month you need to enrich (e.g. 10K, 100K, 1M), I can narrow this down to the best API + estimated cost + latency combination.

If your main requirement is “new lead comes in → call an API → get company size + revenue immediately,” I’d shortlist these:

My recommendation: Apollo

Apollo has a dedicated Organization Enrichment API where you can submit a domain, LinkedIn URL, company name, or website and receive firmographic information including employee count and revenue. It also supports bulk enrichment for up to 10 companies per request.

For example, your pipeline could be:

new lead → extract company domain → Apollo enrichment → size/revenue → CRM

That's a particularly good fit if you're enriching individual inbound leads as they arrive, rather than doing a giant historical database enrichment.

When I'd choose something else

Choose Crustdata if "real-time" is the key requirement. Its positioning is more API-first/fresh-data oriented, and recent user discussions specifically mention it for real-time firmographics, headcount, funding and job changes.

Choose People Data Labs if you're building an engineering-heavy data pipeline and want a raw API rather than a sales platform. It's particularly attractive for high-volume/API-centric workflows.

Choose ZoomInfo if you're an enterprise sales organization where data depth and account hierarchies matter more than cost. It provides revenue, headcount, locations, growth trends and hierarchy data, but typically comes with enterprise pricing.

Choose Clay if you care about match rate more than having one vendor. Clay can waterfall across 200+ data providers, which is useful when Apollo/PDL/etc. can't find a particular company.

One important caveat

Don't evaluate these primarily on their advertised database size. Test your actual leads. Revenue and employee count can vary substantially by provider, especially for startups, subsidiaries, private companies, and international firms. Recent API comparisons also find meaningful differences in coverage and latency between providers.

If you tell me roughly how many leads/month you're enriching (e.g. 1k, 10k, 100k) and whether you have the company domain for each lead, I can narrow this down to the best API + estimated cost per 1,000 enrichments.

When you need a real-time API specifically to enrich company size (headcount) and revenue, the "best" tool depends entirely on your engineering bandwidth, budget , and desired match rate.

The top-performing options split into distinct categories based on how they handle real-time API enrichment:

• People Data Labs (PDL): Best for Developer-First & Scale
  • How it works: Pure data-as-a-service (DaaS) with a robust, highly synchronous API designed to be hit programmatically by backend systems, scoring engines, or AI agents.
  • Data quality: Excellent raw coverage on firmographics (company size and revenue estimates) derived from a massive index of professional and corporate profiles.
  • Pricing: Pay-per-record model, making it cost-effective for high-volume, automated pipeline enrichment.
• Clearbit (now Breeze Intelligence by HubSpot): Best for Marketing & CRM Sync
  • How it works: Offers a clean, real-time company enrichment API that returns over 100 firmographic and technographic attributes (including employee range and revenue) from a simple domain lookup.
  • Data quality: Exceptionally clean, standardized JSON responses. Highly accurate for North American and mainstream global companies.
  • Caveat: Its product roadmap is heavily centered on the HubSpot ecosystem post-acquisition.
• Clay: Best for Multi-Source "Waterfall" Enrichment
  • How it works: Rather than relying on a single database, Clay allows you to build custom API workflows that check multiple data providers in a sequence (a waterfall approach) until it successfully finds the company size and revenue.
  • Data quality: Maximizes match rates (often pushing 90%+) because if Vendor A lacks revenue data for a small B2B company, it instantly queries Vendor B.
  • Caveat: It is an orchestration platform rather than a raw low-latency API endpoint for microservices, though it excels for RevOps automation.
• ZoomInfo Enrich API: Best for Enterprise Accuracy & Org Depth
  • How it works: Enterprise-grade API with robust documentation and OAuth 2.0 support. It uses a search-then-enrich credit structure (searching is free; you only pay credits when data is appended).
  • Data quality: Industry standard for deep enterprise data, accurate revenue tiers, and corporate hierarchy mapping.
  • Caveat: Typically requires a steep annual enterprise contract, making it overkill for lightweight projects.

To help narrow down the ideal choice, tell me:

• What is your estimated monthly API volume (number of leads)?
• Are you looking for a raw developer API (like PDL) or a no-code workflow builder (like Clay)?