yc-reader

Original：🇺🇸 English
Translated

Look up Y Combinator companies, batches, and startup ecosystem data using the yc-oss API (read-only). Use this skill whenever the user wants to research YC-backed startups, find companies in a specific batch or industry, check which YC companies are hiring, explore top YC companies, or analyze startup trends by sector or tag. Triggers include: "YC companies in fintech", "who's in the latest YC batch", "YC startups hiring", "top Y Combinator companies", "find YC companies tagged AI", "W25 batch", "S24 companies", "YC stats", "Y Combinator portfolio", "startup research", "which YC companies do X", "venture research on YC", any mention of Y Combinator, YC batch, or YC-backed companies in the context of startup research, venture analysis, or market intelligence. This is a read-only data source — the API is a static JSON dataset updated daily.

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NPX Install

npx skill4agent add himself65/finance-skills yc-reader

Tags

Translated version includes tags in frontmatter
y-combinatorstartup-researchapi-queryjqcurl

SKILL.md Content

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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:
bash
# 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 RequestEndpointNotes
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-2025.json
, 
summer-2024.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-2025
, 
summer-2024
, 
fall-2025
. Older batches use the same pattern back to 
summer-2005
.

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

bash
# 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

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

Common jq filters

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

Step 5: Diagnostics

If a request fails:
ErrorCauseFix
404 Not Found
Invalid batch, industry, or tag nameCheck 
meta.json
for valid names
Empty array 
[]
No companies match the queryBroaden the search or check spelling
curl: Could not resolve host
No internet connectionCheck network connectivity
Large/slow responseFetching 
companies/all.json
(5,700+ entries)		Use a more specific endpoint or add 
jq
filters
To discover valid batch, industry, and tag names:
bash
# 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.