Harmonic

Find startups before the crowd does

APICapable readiness

About

What is Harmonic

Harmonic maintains a continuously refreshed database of over 35 million companies and 195 million professional profiles, surfacing early signals on startups before they appear in mainstream sources. It's built for VC and growth capital teams, corporate development functions, and GTM leads at mid-market to enterprise companies who need to act on company movements before competitors do. The standout capability is agentic research reports — Harmonic can autonomously generate structured research on companies and founders, reducing manual diligence time. Teams can also map their network's existing connections to a target company, which adds a layer of context most prospecting databases skip entirely. The honest limitation: this is an enterprise-priced, sales-gated product — smaller teams or solo operators will likely find the cost and procurement process a barrier to entry.

Data & Discovery

Capabilities

Key features

Prospecting database

searchable B2B contact + company directory

AI capabilities

autonomous multi-step actions, per-prospect AI research

Data

intent signals, real-time enrichment, firmographic + tech-stack data

Also ships

Chrome extension

No-code automation support

works with major iPaaS platforms

Our verdict

Vanderbuild take

Harmonic is the go-to prospecting database for founders tracking competitive landscapes, GTM leads building target account lists, and account executives who need to get to a company before it's already in everyone else's CRM. On the agentic readiness front, the REST API is solid — you can wrap Harmonic's data layer into your own MCP orchestration cleanly, and its integrations with Clay and n8n mean it fits naturally into agent-driven enrichment pipelines, even if a native MCP server hasn't been confirmed. Budget-wise, this is enterprise-priced with no public tiers and a contact-sales gate, so expect procurement involvement and a real negotiation cycle before you're live. The main limitation we'd flag: if your team doesn't have a dedicated ops or data person to configure alerts, build API workflows, and maintain list hygiene, you'll use maybe 20% of what you're paying for.

Mateusz Sekta

Founder, vanderbuild

The wedge

Agentic stack profile

API

REST

Programmatic access available.

REST API — straightforward to call from any agent or workflow tool. Rate limits and auth vary by plan.

API docs →

Agentic readiness

Capable

Solid API access — wraps cleanly for agent use.

Solid REST or SDK access. No MCP server yet, but easy to wrap in custom agent tooling. Most modern SaaS tools land here.

Stack role

Data source · Researcher

Where this tool slots into an agentic pipeline.

Plays the role of Data source + Researcher in an agentic pipeline. Use it to source contacts, companies, and the raw inputs an agent needs to act; generate per-account briefings and qualification dossiers.

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