Compare/Head to head

Cosign vs Happenstance

Same facts, side by side: starting price, free tier, MCP, API and what each one is actually built for.

Starting price

Cosign

Free Free tier

Cosign is a free a16z network of endorsed startup talent, curated lists and startup jobs. Recruiters hiring for startups get warm context on who is worth calling and a mutual-interest Would Hire signal, plus a free API and MCP server, but it covers the startup world only and has no recruiter seats or exports.

Where Cosign fits

  • Recruiters hiring for venture-backed startups
  • Finding engineers and operators with peer endorsements
  • Warm, mutual-interest outreach to passive talent
  • Teams that want startup talent search inside Claude or ChatGPT

Happenstance searches the people you already know. Free is forever (chat limits, unlimited Sidedoor and connected accounts). Pro is $24/mo billed yearly.

Where Happenstance fits

  • Founders and recruiters who want warm intros from email and calendar history
  • Teams that will pool networks in a Happenstance group
  • Operators who need CSV export of people from chat (Pro)
  • Anyone who will not pay SeekOut prices just to ask 'who do you know at X'

At a glance

DetailCosignHappenstance
Starting priceFree$24/mo
Free tier✓Yes–No
MCP server✓Yes–No
Public API✓Yes–No
Listed underSourcing, Job boardsEmployee referrals, Sourcing

Where they pull apart

Cosign

Stands out: Profiles carry endorsements from named people saying what someone actually did, which is the context a reference call usually gives you. The Would Hire signal only opens a chat when interest is mutual, so outreach starts warm, and the official MCP server lets you search people and jobs from Claude or ChatGPT.

Watch out: Coverage is limited to startups and tech, and the product is new. Many profiles are assembled by AI from public information before the person joins, so details can be wrong. There is no Boolean search, contact data, export or ATS sync, so it is a discovery and warm-intro tool rather than a sourcing database.

Not the right fit for

  • Volume hiring outside tech
  • Teams that need emails, phone numbers or exports
  • Agencies that need ATS or CRM sync

Happenstance

Stands out: It is network search, not Boolean sourcing. Connect Gmail, Outlook, Google Calendar, Contacts, LinkedIn, Twitter, and Instagram, then ask in plain English who you know and why the path exists.

Watch out: Pro's $24/mo is the annual rate. API and MCP use separate credits on top of the seat. This will not find strangers outside your (and your friends'/groups') connected graphs.

Not the right fit for

  • Sourcers who need a 800M stranger graph and cold contact data
  • Buyers who want unlimited chat and MCP included in the $24 seat

Pros and cons

Cosign

  • Completely free, including the API and MCP
  • Named, attributed endorsements on profiles
  • Mutual-interest signals keep outreach warm
  • Startup and tech coverage only
  • AI-built profiles can be inaccurate
  • No contact data, export or ATS sync

Happenstance

  • Free forever for Sidedoor, connected accounts, friends, and groups
  • Pro at $24/mo billed yearly, with CSV export
  • Gmail, Outlook, LinkedIn, Calendar, Contacts, Twitter, Instagram as sources
  • Only as strong as the networks you connect. No cold 800M file
  • API and MCP burn separate credits
  • Chat is capped on Free. Heavy users need Pro

What each one costs

Cosign

Free

Cosign is free. a16z runs it as a free product and lists no paid plans, seats or credits. The public directory API needs no key, and the member MCP server is free with a Cosign account. Confirm current terms on the vendor site.

Checked 2 Nov 2026

Happenstance

$24/mo

Free is $0 forever (limited chat, unlimited Sidedoor, connected accounts, friends, and groups). Pro is $24/mo billed yearly, with higher chat limits and CSV export. Team is $24/seat. API and MCP use separate credits. No credit card for Free. Confirm current terms on the vendor site.

Checked 19 Sep 2026

Common questions

Can you try Cosign or Happenstance for free?
Cosign carries a free tier on our listing.
Does Cosign or Happenstance have an MCP server?
Cosign ships a first party MCP server, so an AI assistant can work the product directly.

Not the pair you wanted?

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Editorial listings, never paid rankings. Prices checked 2 Nov 2026. Confirm current terms on the vendor site. Spot an error?