Best Candidate Enrichment APIs for Recruiting Platform Builders

A recruiting platform builder we spoke with runs a 50+ variable scoring model on every candidate. The model pulls from work history, employer funding stage, publication records, GitHub contributions, and endorsement counts. No single candidate enrichment API returns all of those fields. Lists from any one provider come back "50-60% good," which means 40-50% of candidates either have incomplete data or missing contact information that requires a second or third provider to fill.

If you are building a recruiting platform, an AI-native sourcing tool, or a natural language candidate search product, you need a candidate enrichment API that works as programmable infrastructure your code calls directly. This guide evaluates seven providers on criteria that matter to platform builders: how many data fields per profile they return, whether they cover company data alongside people data, delivery format, data freshness, and pricing predictability.

What Recruiting Platform Builders Actually Need from a Candidate Enrichment API

Most candidate enrichment guides compare Chrome extensions, ATS integrations, and InMail credits. Those features matter for recruiters using a UI, but platform builders have different requirements.

A recruiting platform building a natural language candidate search product needs structured JSON responses that feed directly into search indexes. An LLM-powered candidate scoring pipeline requires 50+ data fields per profile, including endorsement counts, employer funding stage, and certification dates, while a defense-tech talent agency building its own internal database needs to combine structured enrichment data with proprietary context that no external provider has.

These teams share three requirements that recruiter-facing tools do not address:

• Company enrichment alongside candidate enrichment: One ATS platform we spoke with has 1.5 million companies in their database needing funding stage, headcount, and public/private status. Their NL search product cannot rank candidates by employer quality without company data.

• API-native workflows without CSV intermediaries: Platform builders connect APIs directly to scoring engines, matching algorithms, and search indexes. Manual export/import breaks the pipeline.

• Easy to combine with other providers: Because no single provider covers all fields, builders often chain multiple APIs together. The API that fits cleanly into a multi-provider pipeline, with clear credit accounting and predictable response schemas, is easier to build on than one with opaque pricing or inconsistent output formats.

What to Evaluate in a Candidate Enrichment API

How many data fields per profile the API returns

A flat list of "name, email, company, title" is insufficient for any serious candidate scoring or matching system. Evaluate what structured fields the API returns beyond basics: endorsement counts, certification details with issuing dates, employer funding stage, skills with duration inference, education with graduation year, and languages spoken.

One builder we spoke with uses "high agency" signals including collegiate athletic records, open-source contributions, and patents. The people enrichment API that returns the deepest field set reduces how many secondary sources are needed.

Company enrichment alongside people enrichment

Recruiting platform builders consistently describe needing to enrich every company in a candidate's work history with funding stage, headcount, industry classification, and growth trajectory. Without this, a matching engine treats a candidate at a 10-person seed startup the same as one at a public company.

If your API provider offers both company enrichment and people enrichment, you eliminate an entire integration from your stack.

Company-to-people search chaining

One technical recruiter described wanting to "find Series B companies backed by top 30 VCs, then find people at those companies." This requires starting with company-level criteria and pivoting to people search at matching companies. Few candidate enrichment APIs support this pattern natively.

Delivery format: API vs bulk dataset vs webhook

Platform builders loading initial candidate databases need bulk datasets (CSV, Parquet, or JSON lines). Ongoing enrichment of new candidates requires real-time API calls. Job change monitoring requires webhooks that push updates without constant polling.

Evaluate whether the provider supports all three, or only one.

Data freshness spectrum

B2B data decays at roughly 2.1% per month, accumulating to over 22% annually. Outreach response rates drop after 90 days. Freshness exists on a spectrum. One platform builder told us 30-day-old cached data is acceptable for list building, while shortlisted candidates need live enrichment. The provider should support both cached/in-database search (fast, cheap) and real-time enrichment (fresh, higher credit cost).

Pricing predictability

Contact enrichment pricing varies by field type across providers: work emails are cheap, personal emails cost more, phone numbers cost the most. One recruiter described wanting to start at $100-200 per month and scale to $1,000+ as workflows mature. Credit-based models with transparent per-lookup costs are preferable to per-seat licensing for platform builders who need to forecast unit economics.

Compliance guarantees

In July 2025, Proxycurl shut down after the professional network it scraped filed a lawsuit. The company had been running at roughly $10M in annual revenue. Two recruiting platform builders we spoke with explicitly cited compliance concerns: "I want to make sure I'm compliant" when discussing their data sourcing strategy. Compliance determines whether your data provider exists next year.

Seven Candidate Enrichment APIs Compared

Crustdata

Crustdata is an API-first data platform covering 1B+ people profiles and 60M+ companies, built for teams constructing internal tools, AI agents, and recruiting platforms on top of structured data.

Key features:

• People Search API with 60+ filters (title, seniority, skills, geography, years of experience, employer, education, certifications, recent job changes) and nested boolean logic for building precise candidate lists

• People Enrichment API returning 90+ datapoints per profile (work history with dates, skills with endorsement counts, education, languages, certifications)

• Company Enrichment API with 250+ company datapoints (funding stage, headcount, growth rate, revenue, investors, industry)

• Company-to-people search chaining: query companies by criteria, then find people at matching companies

• In-database cached search (3 credits per 100 profiles) plus real-time enrichment (higher credit cost for live data)

• Bulk dataset delivery alongside API access and Watcher webhooks for job change monitoring

• Web Search API for finding publications, patents, and "proof of work" signals

Pros:

• Only provider offering both company and people enrichment in one platform, enabling company-to-people chaining without a second integration

• Credit-based pricing with no charge when no results returned, making unit economics predictable for platform builders

• Supports all three delivery formats: API, bulk datasets, and webhooks

• In-DB search at 3 credits per 100 profiles is cost-effective for list building before selective live enrichment

Cons:

• G2 reviewers note the platform is optimized for technical users, with no point-and-click UI for non-engineers

• Real-time enrichment costs more credits than cached database queries, requiring builders to design cost-aware architectures

Best for: Recruiting platform builders who need company and people enrichment from a single provider, with the flexibility to use cached search for discovery and live enrichment for shortlisted candidates. Teams building auto-updating candidate databases or NL search products.

People Data Labs

People Data Labs is a raw data infrastructure provider with 1.5B+ person records and 62M+ company records, built for engineering teams constructing data products.

Key features:

• Person Enrichment API with one credit per successful match

• Bulk dataset delivery for warehouse-scale enrichment

• Company enrichment as a separate API (62M+ records)

• Identity resolution across multiple input identifiers (email, phone, name + company)

• Free tier: 100 person lookups per month

Pros:

• One of the larger raw people databases available (1.5B+ profiles), useful for teams needing broad coverage

• Pay-per-match pricing (no charge on failed lookups)

• Strong documentation and developer-focused API design

Cons:

• G2 reviewers report data freshness concerns, particularly for non-US profiles where records can lag by months

• Identity merging errors reported at approximately 1 in 1,000 matches, where the API incorrectly links two different people to the same record

• Pro plan ($98/month) includes only 350 person enrichment credits, making per-record cost $0.28 at entry level

• JSON-only delivery format limits flexibility for teams loading into data warehouses that prefer Parquet or CSV

Best for: Engineering teams building people-data products who prioritize raw database breadth over freshness guarantees. Teams with existing data pipeline infrastructure (S3, Snowflake) who can handle their own deduplication and freshness management.

Apollo

Apollo is a sales engagement platform with built-in people and company data, offering enrichment as one feature within a broader outreach stack.

Key features:

• 275M+ contact database with email and phone lookup

• People Enrichment API (requires Professional plan at $79/user/month for API access)

• Intent signals and hiring activity filters

• Built-in sequencing and CRM alongside data

• Free tier: 10,000 credits/month (limited to email, no phone)

Pros:

• Combines enrichment with outreach sequencing in one platform, useful for recruiting teams that also handle candidate engagement

• Large free tier for initial testing

• Hiring activity filters can identify companies actively recruiting for specific roles

Cons:

• Independent testing shows email accuracy around 80%, below the 85-95% threshold recruiting platforms need for automated outreach

• API access locked behind Professional plan ($79/user/month). Basic plan offers no programmatic access.

• Phone Finder costs 500 credits per lookup, making phone enrichment expensive at scale

• Per-seat pricing model conflicts with platform builder economics where a single API key serves thousands of end users

Best for: Small recruiting teams that want enrichment and outreach in one tool without building custom infrastructure. Not well suited for platform builders due to per-seat pricing and limited API availability at lower tiers.

ContactOut

ContactOut specializes in personal email and phone number discovery for recruiting, with a Chrome extension and API tier designed for talent acquisition teams.

Key features:

• 200M work emails, 100M phone numbers, 40M company records

• Chrome extension for sourcing directly from profiles

• REST API available on Team/API plan (custom pricing)

• Search portal with access to 350M professionals

• ATS integrations (Greenhouse, Lever, Bullhorn)

Pros:

• Personal email and direct phone coverage is strong, which matters for reaching passive candidates who do not respond to work email outreach

• Recruiter-specific plan ($199/month annual) includes dedicated ATS integrations

• Hourly data updates on contact records

Cons:

• G2 reviewers note that "unlimited" email/phone claims in marketing are misleading, with actual limits of 2,000 emails and 1,000 phones per month on paid plans

• API access requires custom pricing (Team/API plan), with no published per-credit rate for platform builders to forecast costs

• No company enrichment capability, requiring a separate provider for employer context data

• Chrome-extension-first design means the API is secondary to the UI workflow

Best for: Recruiting agencies and sourcers who need personal email and phone numbers for passive candidate outreach. Works as the contact layer in a waterfall stack alongside a broader enrichment provider.

Coresignal

Coresignal provides bulk professional data at scale, with 859M+ employee profiles and 448M+ job postings, focused on serving data products and recruiting infrastructure.

Key features:

• 859M+ employee profiles, 75M+ company profiles, 448M+ job postings

• Real-time API with 176ms average response time

• Bulk dataset delivery in multiple formats (JSON, JSONL, CSV, Parquet)

• Job posting data alongside people data

• Hiring signals and workforce analytics

Pros:

• Multi-format bulk delivery (Parquet, CSV, JSON, JSONL) gives platform builders flexibility for data warehouse loading

• Job posting dataset (448M+ postings) is a differentiator for teams building candidate-to-job matching features

• Real-time API with fast response times (176ms average)

Cons:

• G2 reviewers report that contact data (email, phone) coverage is weaker than dedicated contact providers, requiring a secondary source for outreach-ready records

• Company enrichment depth is limited compared to providers offering 250+ company fields (funding detail, investor lists, growth trajectories)

• Pricing starts at $49/month but scales quickly for teams needing both bulk datasets and real-time API access

Best for: Data engineering teams building candidate databases and workforce analytics products who need bulk delivery in warehouse-native formats. Teams that prioritize job posting data alongside candidate profiles for matching algorithms.

RocketReach

RocketReach is a contact discovery platform with 700M+ profiles, focused on verified email addresses and phone numbers.

Key features:

• 700M+ professional profiles, 60M companies

• Email and phone lookup with verification

• Chrome extension for profile-based sourcing

• API access on Ultimate plan ($207/month annual)

• CRM integrations (Salesforce, HubSpot, Outreach)

Pros:

• Strong email verification reduces bounce rates for outreach campaigns

• Broad profile coverage (700M+) across industries and geographies

• Recruiter-specific use cases documented in their product

Cons:

• G2 reviewers report that API access requires the Ultimate plan at $207/month ($2,484/year), with only 10,000 lookups per year at that tier

• Export limits are separate from lookup limits, with some plans allowing 10,000 searches but only 500 exports per month

• No company enrichment API. Limited to contact and basic profile data.

• No bulk dataset delivery option, meaning initial database loads must be done through individual API calls

Best for: Recruiting teams that need verified email and phone numbers for outreach campaigns without building custom infrastructure. Works well as a contact-layer provider in a waterfall stack alongside a broader enrichment API.

Proxycurl (Shut Down July 2025)

Proxycurl was a profile-scraping API that returned structured data from professional profiles. The platform it scraped filed a federal lawsuit in January 2025, and Proxycurl shut down by July 2025 despite running at roughly $10M in annual revenue.

Why this matters for platform builders: Any recruiting infrastructure built on Proxycurl needed emergency migration within months. The founder acknowledged that approximately 50% of revenue depended on methods the professional network considered unauthorized. Platform builders evaluating candidate enrichment APIs should verify that providers do not rely solely on account-based scraping, which carries litigation risk from well-resourced platforms.

Former Proxycurl users should evaluate: Crustdata (real-time enrichment without account-based scraping), People Data Labs (bulk datasets), or Coresignal (multi-format delivery).

How to Architect a Candidate Enrichment Stack

Why recruiting platforms use multiple providers, and when to stop

Independent testing shows that single-source enrichment APIs structurally cap at 75-85% accuracy. One recruiting platform builder confirmed this directly: candidate lists from any individual provider are "50-60% good." The remaining 40-50% have missing emails, out-of-date titles, or incomplete work history.

Different providers excel at different things. Some return deep career history and company context. Others specialize in verified personal emails or phone numbers. Most recruiting platforms start by combining two or three providers in a waterfall, where unmatched records from the first provider pass to the second, then the third. Combined coverage across multiple providers reaches 85-95%.

That said, a waterfall is a means to coverage, not a goal in itself. If one provider in your stack consistently returns complete, accurate data for your candidate segments, consolidating to that single provider saves both cost and integration complexity. The right approach is to measure match rates per provider over time and drop the ones that are not pulling their weight.

Waterfall architecture for recruiting platforms

The provider ordering in a waterfall depends on what your platform prioritizes:

• Discovery layer first: Use an in-database search API (low cost, high volume) to build initial candidate lists. Crustdata's in-DB search at 3 credits per 100 profiles is built for this role.

• Contact layer second: Pass shortlisted candidates to a contact-focused provider (ContactOut, RocketReach) for personal email and phone enrichment.

• Verification layer third: Run email verification on all results before outreach to suppress bounces and protect domain reputation.

• Company context throughout: Enrich every employer entity with funding stage, headcount, and growth data. This enables searches like "candidates who worked at Series B companies in New York" that no contact-only provider supports.

Company-to-people chaining as a builder workflow

The workflow platform builders describe most often starts with company criteria (funding stage, investor backing, headcount growth), identifies matching companies, then discovers people at those companies.

With Crustdata, this means querying the Company Discovery API with filters (e.g., Series B, 50-200 employees, backed by specific investors), then using the People Discovery API filtered to those company results. This two-step chain produces targeted candidate pools that recruiter-facing tools cannot replicate because they operate only at the person level.

Compliance and Data Sourcing for Recruiting Platforms

The Proxycurl shutdown is the most concrete example of compliance risk in this market. A $10M ARR company with paying customers lost its business because its data sourcing methods were legally challenged by a platform with resources to litigate.

For recruiting platform builders, the compliance question has three layers:

• Data sourcing method: Does the provider use authorized data partnerships, public web data, or account-based scraping? Account-based approaches carry the highest litigation risk.

• Distribution rights: Some providers restrict how their data can be redistributed. If you are building a platform that serves end-user recruiters, verify that your license allows downstream display and action on enriched data.

• Applicant data regulations: CCPA applies to applicant data with fines of $2,500 per unintentional violation and $7,500 per intentional violation enforced by the California AG. Your enrichment provider should document their compliance posture so you can demonstrate due diligence.

Two platform builders we spoke with independently cited compliance as a primary reason for choosing a paid data provider over continuing with scrapers. One stated it directly: "I've been getting by with some scrapers, but I want to make sure I'm compliant." The provider you choose is a compliance decision as much as a data decision.

Conclusion

Candidate enrichment APIs for recruiting platform builders need to be evaluated on field depth, company enrichment coverage, delivery flexibility, and how easily they combine with other providers in a waterfall. No single provider covers all requirements, which is why the architecture discussion matters as much as the individual provider choice.

Start with the evaluation criteria in this guide. Map your platform's specific needs (scoring model fields, employer context requirements, delivery format, budget constraints) to the provider capabilities. Then architect a stack that combines discovery, enrichment, and contact layers from the providers that fit each role.

Sign up for Crustdata's free tier (100 credits included on signup) to test people and company enrichment together, or book a demo to walk through a recruiting platform architecture with the team.