Contact Enrichment APIs for Developers: PDL, Clearbit, and Alternatives

When You Need an API Instead of a Tool

Off-the-shelf enrichment tools handle most use cases well. But if you're building enrichment into a product — a CRM, a sales platform, a data workflow — you need a programmatic API that returns structured JSON, handles rate limiting predictably, and fits into your architecture.

The developer experience quality varies enormously across enrichment API providers. Some have excellent documentation, SDKs in multiple languages, and clear error codes. Others have enterprise-first designs that assume you'll be calling from a platform integration rather than writing code. This guide covers the APIs actually worth building on.

People Data Labs (PDL): The Developer-Friendly Default

PDL's Person Enrichment API is the closest thing to a standard in developer-built enrichment workflows. The API is well-documented, accepts a wide range of input fields, and returns a comprehensive JSON object with every field it has for a given person.

A minimal call looks like this: a POST request to https://api.peopledatalabs.com/v5/person/enrich with an email address and your API key in the request body. The response includes names, current and past job history, social media profiles, phone numbers, email addresses, education history, and location data — everything PDL has for that person in a single response object.

Key PDL API features:

• Multiple input methods: email, phone, LinkedIn URL, name plus company, name plus location, and more. Higher confidence results when multiple fields are provided.
• Confidence scoring on each result field so you can filter by data certainty.
• Bulk API endpoint for processing up to 100 records per request.
• Python and JavaScript SDKs available on GitHub.
• Free tier: 1,000 API calls/month for development.
• Pay-as-you-go pricing with volume discounts; no minimum contract for lower tiers.

Limitations: Real-world accuracy is 70–85% (not the marketed 98%). Rate limits require handling in your code. International coverage is weaker than US coverage, especially for Asian markets.

Clearbit: Best for Company Enrichment

Clearbit's API splits into two main endpoints: Person Enrichment and Company Enrichment. Following its acquisition by HubSpot, Clearbit's standalone API is less prominently marketed, though it's still available for developers.

Clearbit's strength is company-level data: headcount, technology stack, funding, industry classification, and Alexa rank. The Company Enrichment API takes a domain and returns comprehensive firmographic data. For building lead scoring models that factor in company characteristics, Clearbit is arguably the best option.

For individual contact enrichment (phone numbers, personal emails), PDL has better coverage. For enriching companies and appending company context to contact records, Clearbit competes strongly. Many teams use both: PDL for person enrichment, Clearbit for company enrichment.

Key Clearbit API considerations:

• Company API is consistently excellent for firmographic data
• Person API has lower phone number coverage than PDL
• Pricing has changed with HubSpot acquisition — contact sales for current terms
• Strong Salesforce and HubSpot integrations if you're building within those ecosystems

Full Contact: The Privacy-First Alternative

Full Contact positions itself as a privacy-first enrichment provider with a consent-based data model. Their Enrich API accepts email, phone, or social profile URLs and returns person and company data.

Full Contact's coverage is narrower than PDL's but their data quality on matched records tends to be slightly higher. They're also more explicit about their GDPR compliance posture, which matters if you're building for a European market or a compliance-sensitive enterprise buyer.

The API design is clean and the documentation is good. If privacy compliance is a primary concern in your architecture, Full Contact is worth evaluating alongside PDL.

Apollo.io API: Platform with an API Layer

Apollo is primarily a prospecting platform (search, sequence, enrich) with an API that exposes its data. The API is functional but designed with the assumption that you're enriching within the Apollo ecosystem. It's less flexible for custom workflows than PDL.

If your team is already using Apollo as a prospecting platform, the API is worth using for programmatic access to the data you're already paying for. For teams building custom enrichment infrastructure, PDL is the better foundation.

Building on PDL: Practical Architecture Notes

For teams building enrichment into a CRM or outreach tool using PDL as the underlying API, a few architectural notes from common implementation patterns:

Cache aggressively. PDL data for a given contact doesn't change daily. Cache enrichment results for 30–90 days to avoid paying for redundant API calls. Ziwa's implementation caches for 48 hours — for most B2B enrichment use cases, 30-day caching is fine.

Handle rate limits with exponential backoff. PDL enforces rate limits on API calls. Implement exponential backoff with jitter for retries. For batch processing, process records sequentially with a delay rather than concurrently to stay within rate limits.

Use multiple input fields when available. PDL's match rate improves significantly when you provide more context. Providing email plus LinkedIn URL plus name gets you higher confidence results than email alone. Build your enrichment call to include all available fields, not just the minimum.

Filter by confidence score. PDL returns a likelihood score (0–100) on each result. In most workflows, filtering out results below 70–75 confidence significantly improves data quality at the cost of some coverage.

Ziwa is built on this architecture — PDL API with caching, confidence filtering, and a pay-per-result model that only charges when high-quality data is found. If you want to use enrichment data without building the API integration yourself, Ziwa's credit system gives you API-quality results through a web interface and batch processing tool. For social-profile-based enrichment specifically, Ziwa's Prospects tool is the place to start.