---
name: yc-reader
description: >
  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.
---

# Y Combinator Reader (Read-Only)

Fetches Y Combinator company data from the [yc-oss/api](https://github.com/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 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-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

| 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:

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:

| 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:

```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.