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.

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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.

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Step 2: Identify What the User Needs

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

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.

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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

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

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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

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Step 5: Diagnostics

If a request fails:

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'

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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.

yc-reader

Read-only Y Combinator company data skill using the yc-oss/api.

What it does

Fetches Y Combinator company data for startup and venture research — company profiles, batch listings, industry/tag breakdowns, hiring status, and diversity data. Capabilities include:

• Company collections — top companies, all companies, currently hiring, non-profits, diversity data
• Batch lookup — companies by YC batch (e.g., Winter 2025, Summer 2024)
• Industry filter — companies by industry (fintech, healthcare, B2B, etc.)
• Tag filter — companies by tag (AI, developer tools, SaaS, climate, etc.)
• Metadata — overall YC stats, valid batch/industry/tag names
• Client-side search — find companies by name or description via jq filters

This is a read-only data source. The API serves static JSON files — no write operations exist.

Authentication

None required. The API is public and free — just curl the endpoints.

Triggers

• "YC companies in fintech", "top Y Combinator companies", "latest YC batch"
• "YC startups hiring", "find YC companies tagged AI", "W25 batch"
• "Y Combinator portfolio", "startup research", "which YC companies do X"
• Any mention of Y Combinator or YC in context of startup/venture research

Platform

Works on Claude Code and other CLI-based agents. Does not work on Claude.ai — the sandbox restricts network access required for API calls.

Setup

# As a plugin (recommended — installs all skills)
npx plugins add himself65/finance-skills --plugin finance-social-readers

# Or install just this skill
npx skills add himself65/finance-skills --skill yc-reader

See the main README for more installation options.

Prerequisites

• curl (pre-installed on macOS and most Linux)
• jq (for JSON filtering — brew install jq or apt-get install jq)

Reference files

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

yc-oss API Reference

Complete reference for the yc-oss/api, an unofficial open-source API indexing all publicly launched Y Combinator companies.

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

Authentication: None required — all endpoints are public.

Format: Static JSON files, updated daily via GitHub Actions.

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Company Schema

Each company object contains:

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Endpoints

Metadata

curl -s https://yc-oss.github.io/api/meta.json | jq .

Returns overall statistics: total company count, list of all batches (with counts), all industries (with counts), and all tags (with counts). Use this to discover valid batch/industry/tag names.

Company Collections

# Top YC companies
curl -s https://yc-oss.github.io/api/companies/top.json | jq '.[:5] | .[] | {name, one_liner, batch, team_size}'

# Currently hiring
curl -s https://yc-oss.github.io/api/companies/hiring.json | jq length

Batches

Pattern: batches/{season}-{year}.json

Seasons: winter, spring, summer, fall

# Winter 2026 batch
curl -s https://yc-oss.github.io/api/batches/winter-2026.json | jq length

# Spring 2026 batch
curl -s https://yc-oss.github.io/api/batches/spring-2026.json | jq '.[:5] | .[] | {name, one_liner}'

# Fall 2025 batch
curl -s https://yc-oss.github.io/api/batches/fall-2025.json | jq .

Historical batches go back to summer-2005.

Single company profile

Pattern: batches/{batch-slug}/{company-slug}.json

Both long (winter-2009) and short (w09) batch slugs work. Company slug is the same lowercase-hyphenated form used in the slug field.

# Airbnb profile
curl -s https://yc-oss.github.io/api/batches/winter-2009/airbnb.json | jq .

# Stripe profile
curl -s https://yc-oss.github.io/api/batches/summer-2009/stripe.json | jq '{name, one_liner, team_size, status}'

Industries

Pattern: industries/{industry-name}.json

Use lowercase with hyphens for multi-word names.

Notable industries:

# Fintech companies
curl -s https://yc-oss.github.io/api/industries/fintech.json | jq '.[:10] | .[] | {name, one_liner, batch, isHiring}'

# Healthcare companies hiring
curl -s https://yc-oss.github.io/api/industries/healthcare.json | jq '[.[] | select(.isHiring == true)] | length'

Tags

Pattern: tags/{tag-name}.json

Use lowercase with hyphens for multi-word names.

Notable tags:

# AI-tagged companies
curl -s https://yc-oss.github.io/api/tags/ai.json | jq '.[:10] | .[] | {name, one_liner, batch}'

# Developer tools that are hiring
curl -s https://yc-oss.github.io/api/tags/developer-tools.json | jq '[.[] | select(.isHiring == true)] | .[:10] | .[] | {name, one_liner, website}'

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Research Workflows

Analyze the latest YC batch

# Get batch companies
curl -s https://yc-oss.github.io/api/batches/winter-2026.json | jq length

# Summarize by industry
curl -s https://yc-oss.github.io/api/batches/winter-2026.json | jq 'group_by(.industry) | map({industry: .[0].industry, count: length}) | sort_by(-.count)'

# Find hiring companies in the batch
curl -s https://yc-oss.github.io/api/batches/winter-2026.json | jq '[.[] | select(.isHiring == true)] | .[] | {name, one_liner, website}'

Find fintech/finance startups

# All fintech companies
curl -s https://yc-oss.github.io/api/industries/fintech.json | jq '.[:20] | .[] | {name, one_liner, batch, team_size, status}'

# Active fintech companies that are hiring
curl -s https://yc-oss.github.io/api/industries/fintech.json | jq '[.[] | select(.isHiring == true and .status == "Active")] | .[:15] | .[] | {name, one_liner, batch, team_size, website}'

Track hiring trends (growth signal)

# Largest hiring companies
curl -s https://yc-oss.github.io/api/companies/hiring.json | jq 'sort_by(-.team_size) | .[:20] | .[] | {name, team_size, industry, batch}'

# Hiring companies in AI
curl -s https://yc-oss.github.io/api/tags/ai.json | jq '[.[] | select(.isHiring == true)] | sort_by(-.team_size) | .[:15] | .[] | {name, team_size, one_liner}'

Search for a specific company

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

# Search in one-liners
curl -s https://yc-oss.github.io/api/companies/all.json | jq '[.[] | select(.one_liner | test("payment"; "i"))] | .[:10] | .[] | {name, one_liner, batch}'

Top companies analysis

# Top companies with details
curl -s https://yc-oss.github.io/api/companies/top.json | jq '.[] | {name, one_liner, batch, team_size, status, industry}'

# Top companies by team size
curl -s https://yc-oss.github.io/api/companies/top.json | jq 'sort_by(-.team_size) | .[:10] | .[] | {name, team_size, batch}'

Diversity data

# Women-founded companies in latest batch
curl -s https://yc-oss.github.io/api/companies/women-founded.json | jq '[.[] | select(.batch == "Winter 2026")] | .[] | {name, one_liner}'

# Count by diversity category
curl -s https://yc-oss.github.io/api/companies/black-founded.json | jq length
curl -s https://yc-oss.github.io/api/companies/women-founded.json | jq length

Export for analysis

# CSV export (name, batch, industry, team_size, status)
curl -s https://yc-oss.github.io/api/companies/top.json | jq -r '.[] | [.name, .batch, .industry, .team_size, .status] | @csv' > yc_top.csv

# JSON subset for processing
curl -s https://yc-oss.github.io/api/industries/fintech.json | jq '[.[] | {name, one_liner, batch, team_size, website, isHiring}]' > fintech_yc.json

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Discovering Valid Names

When the user asks for a batch, industry, or tag that you're not sure about, query meta.json:

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

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

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

# Search for a tag name
curl -s https://yc-oss.github.io/api/meta.json | jq '[.tags[] | select(.name | test("fintech"; "i"))]'

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Error Reference

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Limitations

• Read-only — Static JSON files, no search API or query parameters
• No founder details — Company profiles don't include individual founder names or bios
• No funding data — Funding amounts, valuations, and investor details are not included
• No revenue/financial data — Only public metadata (team size, hiring status, industry)
• Updated daily — Data may be up to 24 hours behind YC's live directory
• Publicly launched only — Stealth companies not yet launched on YC are excluded