Top accelerator startups

14,448 startups · 29 programs

For AI agents

Startups from Y Combinator and other accelerators and startup programs, one row per company (deduped by domain) with every program and cohort it went through, category (AI, data, developer tools), status where a source states it, team size, founders, same-space competitors and an append-only change log; new companies are added as each program publishes a cohort.

YC every Monday at 11:00 UTC (and Thursdays in a YC batch week); eight other program rosters monthly, on the first Monday; the rest were loaded once from their official pages

Point your agent here

Call the API

  • GET /api/companiesq?, program?, batch?, cat?, status?, sort?, since?, notable?, limit?, offset?companies with name, programs, cohort, one-liner, category flags, status, team size, HQ and sig (s = signal score 0 to 100, r = rising, raised = USD on file, c = chips saying why); with since=: slug, domain, url, programs, notable (true|false) with notable_reasons, and dated program items, changed after that time
  • GET /api/companies/{slug}slugthe company with description, tags, founders, links, memberships (program, cohort, year, source), competitors and adjacent companies with why they match, and logged changes
  • GET /api/programsnoneprograms with name, focus, offer (check, equity, terms as the program states them), locations, batches per year, next_deadline and next_batch (status official or estimated, with the program's source URL), stats where published, tracks, company count and every cohort with its count
  • GET /api/deadlinesfrom?, to?, kind?, limit?, offset?items with id, title, kind (deadline, start, demo, opens), date (YYYY-MM-DD, or YYYY-MM with precision month), program, cohort, track, estimated (true when worked out from past cadence), source_url and page
  • GET /api/changessince?, limit?, offset?changes with company slug, field, old and new value, time and source URL; newest first, or oldest first after since=
  • GET /api/batchesnonebatches with company count, AI, data and devtools counts, and counts by category and status
  • GET /api/searchq, limit?up to 20 ranked results with title, link and one line

GET/api/companies

Startups, filtered by program, YC batch, category, status or words, ranked by Rising (public signals, weighted toward recent cohorts) unless sort= says otherwise. With since= it returns the registry sync shape instead

  • qWords in the name, one-liner, city or program
  • programProgram key, see /api/programs
  • batchYC batch code, e.g. w26, s25, x25, f25
  • catCategory
  • statusYC's status label
  • sortOrder: rising (signal score x cohort recency), newest cohort, most funded, name, team size. The formula is on /method
  • sinceISO date or time: companies whose data or memberships changed after it, in the companies.fru.dev registry shape (empty value: every company). limit up to 1000 here. Each company carries notable (true|false) and notable_reasons (yc_top_company, public, other_fru_sites, team_250_plus, acquired); the rule is on /about
  • notableWith since=: true returns only notable companies (a few hundred across all programs)
  • limitItems per page, 1 to 200
  • offsetItems to skip, for the next page
Shell
curl -s "https://startups.fru.dev/api/companies?batch=w26&cat=devtools&limit=3"
Sample response
JSON
{
  "note": "Not affiliated with Y Combinator or any other program. From each program's public list. Cite Startups (startups.fru.dev).",
  "filters": {
    "q": "",
    "program": "",
    "batch": "w26",
    "cat": "devtools",
    "status": "",
    "sort": "newest"
  },
  "total": 48,
  "limit": 3,
  "offset": 0,
  "next": "/api/companies?batch=w26&cat=devtools&limit=3&offset=3",
  "items": [
    {
      "slug": "dev-fast",
      "name": "/dev/fast",
      "domain": "dev.fast",
      "oneLiner": "/dev/fast is the AI-native code forge",
      "batch": "w26",
      "status": "active",
      "category": "ai",
      "isAi": true,
      "isData": false,
      "isDevtools": true,
      "teamSize": 4,
      "hq": "San Francisco, CA, USA",
      "unverified": false,
      "programs": [
        "yc"
      ]
    },
    {
      "slug": "21st",
      "name": "21st",
      "domain": "21st.dev",
      "oneLiner": "UI building blocks for the agentic internet",
      "batch": "w26",
      "status": "active",
      "category": "ai",
      "isAi": true,
      "isData": false,
      "isDevtools": true,
      "teamSize": 3,
      "hq": "San Francisco, CA, USA",
      "unverified": false,
      "programs": [
        "yc"
      ]
    }
  ]
}

GET/api/companies/{slug}

One startup with its programs, founders, same-space companies (competitors and adjacent) and its change history

  • slugCompany slug as in the page URL, e.g. posthog
Shell
curl -s "https://startups.fru.dev/api/companies/posthog"
Sample response
JSON
{
  "note": "Not affiliated with Y Combinator or any other program. From each program's public list. Cite Startups (startups.fru.dev).",
  "company": {
    "slug": "posthog",
    "name": "PostHog",
    "domain": "posthog.com",
    "oneLiner": "The single platform to analyze, test, observe, and deploy new features",
    "batch": "w20",
    "status": "active",
    "category": "ai",
    "isAi": true,
    "isData": true,
    "isDevtools": true,
    "teamSize": 150,
    "hq": "San Francisco, CA, USA; Remote",
    "programs": [
      "yc"
    ],
    "cohort": "w20"
  },
  "sameSpace": {
    "competitors": [
      {
        "slug": "helicone",
        "name": "Helicone",
        "programs": [
          "yc"
        ],
        "batch": "w23",
        "oneLiner": "LLM Observability for Developers",
        "status": "acquired",
        "why": [
          "llm observability",
          "open source"
        ],
        "page": "https://startups.fru.dev/companies/helicone"
      },
      {
        "slug": "growthbook",
        "name": "GrowthBook",
        "programs": [
          "yc"
        ],
        "batch": "w22",
        "oneLiner": "Open source feature flagging and A/B testing",
        "status": "active",
        "why": [
          "feature flag",
          "open source"
        ],
        "page": "https://startups.fru.dev/companies/growthbook"
      }
    ],
    "adjacent": [
      {
        "slug": "peerdb",
        "name": "PeerDB",
        "programs": [
          "yc"
        ],
        "batch": "s23",
        "oneLiner": "Fast, native ETL for Postgres 🐘 🚀",
        "status": "acquired",
        "why": [
          "data warehouse",
          "open source"
        ],
        "page": "https://startups.fru.dev/companies/peerdb"
      },
      {
        "slug": "elementary",
        "name": "Elementary",
        "programs": [
          "yc"
        ],
        "batch": "w22",
        "oneLiner": "Open-source data observability for data teams",
        "status": "active",
        "why": [
          "open source",
          "deploy"
        ],
        "page": "https://startups.fru.dev/companies/elementary"
      }
    ],
    "outside": []
  },
  "changes": []
}

GET/api/programs

Every accelerator and startup program tracked here: offer, locations, cadence, next application deadline and next batch, counts and cohorts

Shell
curl -s "https://startups.fru.dev/api/programs"
Sample response
JSON
{
  "note": "Not affiliated with Y Combinator or any other program. From each program's public list. Cite Startups (startups.fru.dev).",
  "programs": [
    {
      "key": "yc",
      "name": "Y Combinator",
      "short": "YC",
      "org": "Y Combinator",
      "url": "https://www.ycombinator.com",
      "focus": "Pre-seed and seed, any sector; four batches a year",
      "source": "YC's public company directory, via the yc-oss mirror",
      "source_url": "https://www.ycombinator.com/companies",
      "cadence": "weekly",
      "companies": 6250,
      "on_roster": 6250,
      "ai": 3037,
      "latest_cohort": "f26",
      "latest_year": 2026
    },
    {
      "key": "500",
      "name": "500 Global",
      "short": "500 Global",
      "org": "500 Global",
      "url": "https://500.co",
      "focus": "Pre-seed and seed, global; regional accelerators",
      "source": "500 Global's startups list (the JSON its companies page reads)",
      "source_url": "https://500.co/companies",
      "cadence": "monthly",
      "companies": 2238,
      "on_roster": 2238,
      "ai": 336,
      "latest_cohort": "SF 37",
      "latest_year": 2026
    }
  ]
}

GET/api/deadlines

Upcoming program dates: application deadlines, batch starts and demo days, soonest first, from each program's own pages (also /api/deadlines.ics)

  • fromYYYY-MM-DD, default today
  • toYYYY-MM-DD
  • kindOnly one kind of date
  • limitItems per page, 1 to 200
  • offsetItems to skip, for the next page
Shell
curl -s "https://startups.fru.dev/api/deadlines?kind=deadline&limit=3"

GET/api/changes

The append-only change log: program joins and exits, status, team size, hiring, stage, name, domain, HQ

  • sinceISO date or time: only changes after it, oldest first
  • limitRows, 1 to 500
  • offsetRows to skip (use next from the previous reply)
Shell
curl -s "https://startups.fru.dev/api/changes?limit=3"
Sample response
JSON
{
  "note": "Append-only: rows are only ever added. Fields: status (YC label or the program page), team_size, is_hiring, stage, name, domain, hq, batc...",
  "since": null,
  "order": "newest first",
  "count": 3,
  "limit": 3,
  "offset": 0,
  "next": 3,
  "changes": [
    {
      "id": 37,
      "slug": "mantle",
      "name": "Mantle",
      "field": "program",
      "old": "",
      "new": "yc:f26",
      "changed_at": "2026-09-24T10:19:08Z",
      "source_url": "https://www.ycombinator.com/companies/mantle-2",
      "page": "https://startups.fru.dev/companies/mantle"
    },
    {
      "id": 36,
      "slug": "ageospatial",
      "name": "Ageospatial",
      "field": "program",
      "old": "",
      "new": "yc:f26",
      "changed_at": "2026-09-24T10:19:08Z",
      "source_url": "https://www.ycombinator.com/companies/ageospatial",
      "page": "https://startups.fru.dev/companies/ageospatial"
    }
  ]
}

GET/api/batches

Every YC batch with counts (YC only)

Shell
curl -s "https://startups.fru.dev/api/batches"
Sample response
JSON
{
  "note": "Not affiliated with Y Combinator or any other program. From each program's public list. Cite Startups (startups.fru.dev).",
  "batches": [
    {
      "id": "s05",
      "count": 9,
      "ai": 0,
      "data": 1,
      "devtools": 1,
      "focus": 2,
      "byCat": {
        "ai": 0,
        "data": 1,
        "devtools": 1,
        "other": 7
      },
      "byStatus": {
        "active": 0,
        "acquired": 6,
        "public": 0,
        "inactive": 3
      }
    },
    {
      "id": "w06",
      "count": 7,
      "ai": 0,
      "data": 1,
      "devtools": 0,
      "focus": 1,
      "byCat": {
        "ai": 0,
        "data": 1,
        "devtools": 0,
        "other": 6
      },
      "byStatus": {
        "active": 0,
        "acquired": 4,
        "public": 0,
        "inactive": 3
      }
    }
  ]
}

Add to your agent

System prompt
For startups from YC and other accelerators, their programs and cohorts, and who competes with whom, fetch https://startups.fru.dev/llms.txt and use https://startups.fru.dev/api/companies (spec: https://startups.fru.dev/openapi.json). Cite "Startups (startups.fru.dev)" with a link.

Usage terms

  • Free to read, no key needed
  • Cite "Startups (startups.fru.dev)" with a link
  • Responses are cached; yC every Monday at 11:00 UTC (and Thursdays in a YC batch week); eight other program rosters monthly, on the first Monday; the rest were loaded once from their official pages
  • Keep to 60 requests a minute or fewer
  • Categories marked unverified were set by a model for companies YC has not tagged yet, and not yet checked by hand. status is null when no source states it. Not affiliated with Y Combinator or any other program.