yc-reader
Look up Y Combinator companies and batches from the public yc-oss API, a static JSON dataset refreshed daily: company profiles, batch rosters (e.g. W25, S24), companies by industry or tag, top companies, who is hiring, founder-diversity lists, and overall YC stats. Use this skill whenever the user asks about YC-backed startups, a YC batch, YC companies in a sector or tag or that are hiring, the Y Combinator portfolio, or startup and venture research that draws on YC data. Read-only.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/himself65/finance-skills --skill yc-reader- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads yc-reader automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Y Combinator Reader (Read-Only)
If your host has not already executed the shell probes below (for example, in Codex), run the commands inside the ! wrappers with its shell tool before choosing a setup path. Use the actual output; if shell access is unavailable, report that limitation.
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
-sflag with curl to suppress progress output - Pipe through
jqfor readable output and filtering - Avoid fetching
companies/all.jsonunless necessary — it's a large response (~5,700 companies). Prefer more specific endpoints (batches, industries, tags) when possible - Use
jqselect/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-2025notWinter 2025orW25 - Tag and industry names are lowercase with hyphens —
developer-toolsnotDeveloper 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
Summarize rather than dump JSON. For each company, give the name, one-liner, batch, team size, status, hiring status (a growth signal), and website. For a batch, lead with its size and notable companies; for an industry or tag, the count and which companies are top or hiring; for research questions, aggregate stats such as counts, common industries, and team-size distribution. Mention that the dataset refreshes daily.
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.
FAQ
What does the yc-reader skill do?
Look up Y Combinator companies and batches from the public yc-oss API, a static JSON dataset refreshed daily: company profiles, batch rosters (e.g. W25, S24), companies by industry or tag, top companies, who is hiring, founder-diversity lists, and overall YC stats. Use this skill whenever the user asks about YC-backed startups, a YC batch, YC companies in a sector or tag or that are hiring, the Y Combinator portfolio, or startup and venture research that draws on YC data. Read-only.
How do I install yc-reader?
Run npx skills add https://github.com/himself65/finance-skills --skill yc-reader in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/yc-reader/ (personal) or .claude/skills/yc-reader/ (project).
Which AI agents can use yc-reader?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is yc-reader safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains yc-reader?
It is published by himself65 in himself65/finance-skills. It has 2,891 recorded installs.
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