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

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)?

If your primary goal is to enrich new B2B leads with company size (employee count) and revenue via a real-time API, I'd narrow it down like this:

My recommendations by use case

For most SaaS products or CRM enrichment:
Clearbit remains one of the easiest APIs if all you need is:

• employee count
• estimated revenue
• industry
• location
• technologies
• company description

It accepts a company domain and returns over 100 firmographic attributes with low latency.

For sales teams:
Apollo offers a strong organization enrichment endpoint that returns:

• employee count
• annual revenue
• funding
• industry
• headquarters
• phone
• LinkedIn
• company hierarchy

It also supports enriching by domain, website, company name, or LinkedIn URL.

For developers building enrichment into a product:
People Data Labs is often the strongest choice when you need:

• REST API
• SDKs
• high request volumes
• flexible matching logic
• custom pipelines

It's designed more as a data platform than a sales tool.

If accuracy is the priority

No provider has perfect coverage. Many RevOps teams now use waterfall enrichment, trying multiple providers in sequence until one returns a match, because this typically improves coverage compared with relying on a single vendor.

Overall ranking

1. Apollo — Best overall balance of API quality, company data, pricing, and additional sales capabilities.
2. People Data Labs — Best for developer-first products and large-scale API usage.
3. Clearbit (HubSpot Breeze Intelligence) — Excellent for marketing and inbound lead enrichment, especially if you're already using HubSpot.
4. ZoomInfo — Highest-end enterprise option with extensive company intelligence, but generally the most expensive.
5. Cognism — Best if your business focuses on European markets and compliance.

If you're enriching leads in real time (for example, in a signup flow, CRM webhook, or automation platform like Zapier, Make, or n8n), I'd generally recommend:

• Apollo if you also want prospecting and sales workflows.
• People Data Labs if you're building a product around enrichment.
• Clearbit if you primarily need fast, reliable company firmographics from a domain.

Enriching new leads with company size (headcount) and revenue via a real-time API depends heavily on your tech stack, budget, and desired match rates. Because single-vendor databases often miss 20% to 30% of specific revenue figures, modern RevOps teams typically choose between specialized developer APIs, all-in-one platforms, or multi-source waterfall builders.

The top choices for real-time company size and revenue enrichment break down as follows:

1. Best for Workflow & Maximum Match Rate: Clay

If you want to pull revenue and company size without relying on a single database, Clay is the leading workflow orchestrator.

• How it works: It acts as a waterfall enrichment tool, connecting to over 100 data providers (including providers like Clearbit, Dropcontact, and Crustdata) in a single automated table sequence. If Provider A doesn't have the revenue field, it instantly queries Provider B, C, and D until it finds a match.
• Best for: RevOps engineers and technical teams who want the highest possible match rate for firmographics.
• API / Real-time: Excellent webhook and table-triggered automations, though it requires light setup.

2. Best for Raw Developer Data & Scale: People Data Labs (PDL)

If you are writing custom code or building a product backend and need a clean, developer-first REST API, People Data Labs is a top contender.

• How it works: It indexes billions of professional and corporate data points globally, offering a dedicated Company Enrichment endpoint that returns size ranges, industry, and estimated revenue.
• Pricing: Pay-per-record model (often scaling down to a few cents per request), avoiding rigid enterprise lock-ins.
• Best for: Engineering teams building programmatic data pipelines.

3. Best for All-in-One Sales & CRM Sync: Apollo.io

If your goal is not just an API call, but a platform that also handles prospecting, emailing, and native CRM enrichment, Apollo.io provides a robust API.

• How it works: Apollo's API allows you to programmatically submit a domain or company name and append firmographic details like employee count and revenue tiers directly into your workflows.
• Best for: Cost-sensitive or mid-market sales teams looking to consolidate prospecting and enrichment into a single tool.

4. Best for Enterprise & Deep Firmographics: ZoomInfo

If you are targeting mid-market to Fortune 500 companies and need granular organizational depth, ZoomInfo Enrich is the established enterprise standard.

• How it works: Provides robust real-time API matching for firmographics, technographics, and hierarchy data.
• The Catch: Requires a hefty annual enterprise contract ($15k+) and typically hides transparent API pricing behind a sales call.

Quick Recommendation Summary

• Choose Clay if you want the highest match rate for revenue/size via a multi-source waterfall.
• Choose People Data Labs if you want a clean, pay-per-call developer API.
• Choose Apollo.io if you need a budget-friendly hybrid of an enrichment API and a sales engagement platform.

To help narrow this down, could you share:

• Expected monthly volume of API requests/leads?
• Whether you are building a custom application (needing a raw API like PDL) or connecting to an existing CRM/Workflow tool (like HubSpot, Salesforce, or Clay)?

If your main goal is to enrich new leads in real time with company size (employee count) and revenue, I'd prioritize API quality, match rate, latency, and pricing over UI features.

Here's how the leading options compare:

Best overall: Crustdata

If freshness matters—for example, routing inbound leads based on current company growth or size—Crustdata stands out because it enriches from multiple sources and offers live enrichment rather than relying only on periodically refreshed databases. Besides employee count and revenue, it also includes funding, hiring activity, web traffic, and other growth signals.

Best developer experience: CompanyEnrich

If you're building an application that needs a straightforward REST API, CompanyEnrich is a strong option. It accepts a company domain or name and returns fields including:

• Employee count
• Revenue range
• Industry
• Headquarters
• Technologies
• Company metadata

It's designed specifically for CRM and lead enrichment workflows.

Best enterprise: ZoomInfo

ZoomInfo remains one of the deepest B2B datasets, with extensive firmographic coverage and high-quality company information. It's an excellent choice for large sales organizations, though it's typically much more expensive than API-first alternatives.

Best if you're already using HubSpot

If your leads already flow through HubSpot, Clearbit's capabilities (now part of Breeze Intelligence) provide seamless enrichment with minimal engineering effort.

Best value for API-first startups

People Data Labs offers robust APIs with good coverage and is commonly chosen when you need to enrich millions of records programmatically. It integrates well into custom data pipelines.

Recommendation by use case

• Highest data freshness: Crustdata
• Simplest REST API: CompanyEnrich
• Largest enterprise dataset: ZoomInfo
• HubSpot-native workflows: Clearbit/Breeze Intelligence
• Large-scale API enrichment: People Data Labs

If all you need is company size and annual revenue immediately after someone submits a lead form, I'd narrow it to:

1. Crustdata
2. CompanyEnrich
3. People Data Labs

These all provide APIs suitable for enriching leads in real time and returning firmographic data that can be written back into your CRM or used for lead routing.

When looking for the best data enrichment tool with a real-time API to append company size (headcount) and revenue , the "best" choice depends on whether you want a single high-accuracy source or a multi-source "waterfall" architecture. Single-source APIs return quickly, but multi-source orchestration ensures you actually find the revenue and size data instead of hitting null values.

The top-performing data enrichment options with real-time APIs are categorized below by their strengths:

• Clay is the top choice for Revenue Operations teams wanting full command over their data providers. It features a flexible workspace that lets you run real-time waterfall enrichment —querying 150+ data providers (like Clearbit, Dropcontact, and Kaspr) in a single sequence until it finds the company size and revenue data.
• People Data Labs (PDL) is a developer-first, raw API provider ideal for engineering teams and AI workflows. It indexes professional and company data extensively and provides clean REST and SDK endpoints to return firmographics like employee count and revenue matching via a company domain or LinkedIn URL.
• Clearbit (Breeze Intelligence) specializes in fast, real-time API enrichment built specifically for instant form auto-population and CRM synchronization (primarily optimized for HubSpot). It automatically appends firmographics like size and tech stack the second an inbound lead provides an email or domain.
• Crustdata is an emerging favorite for modern, real-time B2B data and live signals. It offers a robust Company Enrichment API that aggregates dynamic headcount changes, live web traffic, and financial/revenue data from over 15 sources on demand.
• Apollo.io offers an all-in-one GTM platform with a powerful, developer-friendly API. It provides deep firmographic filtering (including employee ranges and funding/revenue brackets) and is a cost-effective route if you also want built-in email verification and outbound sequencing.

To help narrow down the ideal API for your stack, could you share:

• Expected API volume (e.g., hundreds vs. tens of thousands of requests per month)?
• Your primary CRM or tech stack (HubSpot, Salesforce, or a custom internal database)?
• Whether you prefer a single provider API or a waterfall builder like Clay?