Yc Reader

Y Combinator Reader (Read-Only)

Fetches Y Combinator company data from the yc-oss/api, an unofficial open-source API that indexes all publicly launched YC companies. The data is sourced from YC's Algolia search index and updated daily via GitHub Actions.

This is a read-only data source. It provides company profiles, batch listings, industry/tag breakdowns, hiring status, and diversity data. No write operations exist — the API serves static JSON files.

No authentication required. The API is public and free. Just use curl to fetch JSON endpoints.

Step 1: Verify Prerequisites

This skill only needs curl (to fetch data) and jq (to parse/filter JSON). Both are pre-installed on most systems.

!`(command -v curl > /dev/null && echo "CURL_OK" || echo "CURL_MISSING") && (command -v jq > /dev/null && echo "JQ_OK" || echo "JQ_MISSING")`

If JQ_MISSING, install it:

# macOS
brew install jq

# Linux (Debian/Ubuntu)
sudo apt-get install jq

If jq is unavailable, you can still fetch raw JSON with curl and parse it inline with Python or other tools — but jq makes filtering much easier.

Step 2: Identify What the User Needs

Match the user's request to the appropriate endpoint. See references/api_reference.md for full details.

| User Request | Endpoint | Notes |

|---|---|---|

| Overall YC stats | meta.json | Company count, batch list, industry/tag lists |

| All companies | companies/all.json | Full dataset (~5,700 companies) — large response |

| Top companies | companies/top.json | ~91 top-performing YC companies |

| Companies hiring | companies/hiring.json | ~1,400 currently hiring |

| Non-profit companies | companies/nonprofit.json | YC-backed non-profits |

| Diversity data | companies/black-founded.json, hispanic-latino-founded.json, women-founded.json | Founder diversity |

| Specific batch | batches/{batch-name}.json | e.g., winter-2026.json, spring-2026.json, fall-2025.json |

| Single company profile | batches/{batch-name}/{slug}.json | e.g., batches/summer-2009/stripe.json, batches/winter-2009/airbnb.json |

| By industry | industries/{industry}.json | e.g., fintech.json, healthcare.json |

| By tag | tags/{tag}.json | e.g., ai.json, developer-tools.json |

Batch name format

Batches use {season}-{year} format: winter-2026, spring-2026, summer-2026, fall-2025. Older batches follow the same pattern back to summer-2005. The short form (w09, s21) also works for the per-company endpoint.

Industry and tag name format

Use lowercase with hyphens for multi-word names: real-estate, developer-tools, machine-learning.

Step 3: Execute the Request

Base URL

https://yc-oss.github.io/api/

General pattern

# Fetch and pretty-print
curl -s https://yc-oss.github.io/api/companies/top.json | jq .

# Count companies in a result
curl -s https://yc-oss.github.io/api/batches/winter-2025.json | jq length

# Filter by field (e.g., hiring companies in a batch)
curl -s https://yc-oss.github.io/api/batches/winter-2025.json | jq '[.[] | select(.isHiring == true)]'

# Extract specific fields
curl -s https://yc-oss.github.io/api/companies/top.json | jq '.[] | {name, one_liner, batch, team_size, website}'

# Search by name (case-insensitive)
curl -s https://yc-oss.github.io/api/companies/all.json | jq '[.[] | select(.name | test("stripe"; "i"))]'

Key rules

• Use -s flag with curl to suppress progress output
• Pipe through jq for readable output and filtering
• Avoid fetching companies/all.json unless necessary — it's a large response (~5,700 companies). Prefer more specific endpoints (batches, industries, tags) when possible
• Use jq select/filter to narrow results client-side when the API doesn't have a specific endpoint for what the user wants
• Batch names are lowercase with hyphens — winter-2025 not Winter 2025 or W25
• Tag and industry names are lowercase with hyphens — developer-tools not Developer Tools

Common jq filters

| Filter | Purpose |

|---|---|

| jq length | Count results |

| jq '.[0]' | First company |

| jq '.[:10]' | First 10 companies |

| jq '[.[] \| select(.isHiring == true)]' | Only hiring companies |

| jq '[.[] \| select(.status == "Active")]' | Only active companies |

| jq '[.[] \| select(.team_size > 100)]' | Companies with 100+ employees |

| jq '.[] \| {name, one_liner, batch, website}' | Select specific fields |

| jq '[.[] \| select(.name \| test("query"; "i"))]' | Search by name |

| jq 'sort_by(-.team_size) \| .[:10]' | Top 10 by team size |

Step 4: Present the Results

After fetching data, present it clearly for startup/venture research:

• Summarize key data — company name, one-liner, batch, team size, status, and website
• Highlight hiring status — note which companies are actively hiring (growth signal)
• Include website URLs when the user might want to visit the company
• For batch listings, summarize the batch size and notable companies
• For industry/tag queries, highlight trends (how many companies, which are top/hiring)
• For research queries, provide aggregate stats (count, common industries, team size distribution)
• Note the data freshness — the API updates daily, so data is near-real-time

Step 5: Diagnostics

If a request fails:

| Error | Cause | Fix |

|-------|-------|-----|

| 404 Not Found | Invalid batch, industry, or tag name | Check meta.json for valid names |

| Empty array [] | No companies match the query | Broaden the search or check spelling |

| curl: Could not resolve host | No internet connection | Check network connectivity |

| Large/slow response | Fetching companies/all.json (5,700+ entries) | Use a more specific endpoint or add jq filters |

To discover valid batch, industry, and tag names:

# List all batches
curl -s https://yc-oss.github.io/api/meta.json | jq '.batches[].name'

# List all industries
curl -s https://yc-oss.github.io/api/meta.json | jq '.industries[].name'

# List all tags (there are 333+)
curl -s https://yc-oss.github.io/api/meta.json | jq '.tags[].name'

Reference Files

• references/api_reference.md — Complete endpoint reference with company schema, all endpoint URLs, and research workflow examples

Read the reference file when you need the exact company field schema, valid batch/industry/tag names, or detailed research workflow patterns.