@cyanheads/nonprofit-explorer-mcp-server
Search and explore 1.8M+ US nonprofits, fetch Form 990 financials, and access IRS filing history via MCP. STDIO or Streamable HTTP.
3 Tools
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**Public Hosted Server:** [https://nonprofit-explorer.caseyjhand.com/mcp](https://nonprofit-explorer.caseyjhand.com/mcp)
---
## Overview
IRS Form 990 data for 1.8M+ tax-exempt organizations, via the ProPublica Nonprofit Explorer API. Search by name, fetch an org's financial snapshot, and pull its full filing history.
### Tools
| Tool | Description |
|:---|:---|
| `nonprofit_search_organizations` | Search 1.8M+ IRS-recognized tax-exempt organizations by name, keyword, city, or phrase with optional state, NTEE sector, and 501(c) filters |
| `nonprofit_get_organization` | Full profile by EIN: legal identity, IRS classification, filing requirements, newest-return metadata, and latest extracted financial snapshot |
| `nonprofit_get_filings` | Form 990 history by EIN, optionally filtered by fiscal year: financials, fundraising figures, executive compensation, and source PDF links |
## Capability reference
### `nonprofit_search_organizations` tool
- Full-text query — supports quoted phrases (`"Red Cross"`), required terms (`+evanston`), excluded terms (`-dental`)
- Optional filters: state/territory name or postal code (including military codes and `ZZ` for foreign entities), NTEE major sector (`1`–`10` or a case-insensitive major letter), and 501(c) subsection code (`3` covers both public charities and private foundations — see `foundation_type` on `nonprofit_get_organization` to tell them apart). Names and letters normalize to the upstream codes shown in `active_filters`; unrecognized states are rejected before a request
- `sub_name` is the upstream legal name with an optional secondary line; it can repeat `name` or be null
- Paginated at 25 per page (`page`, zero-indexed); `num_pages`, `per_page`, and `page_offset` track position
- API caps total results at 10,000 — `total_results === 10000` means the actual count may be higher, and a page whose offset reaches that ceiling is refused (`pagination_ceiling`)
- Zero matches and a page past the last one both succeed with an empty `organizations` array and a `notice` explaining which case it is
- Returns EINs — pass to `nonprofit_get_organization` or `nonprofit_get_filings` for details
---
### `nonprofit_get_organization` tool
- Accepts EIN as integer (`530196605`) or string with or without hyphen (`"53-0196605"`); use `nonprofit_search_organizations` first if you only have an org name
- Returns legal identity, address, NTEE code, 501(c) type, and IRS ruling date
- IRS Business Master File standing: deductibility (including the deductible-by-treaty case), exemption status, and public-charity vs. private-foundation classification — each decoded from its IRS code with the raw code retained
- `latest_filing` is the latest extracted financial snapshot: revenue, expenses, assets, liabilities, net assets, and source PDF link. `latest_return` separately identifies the newest return across extracted and PDF-only histories; a newer return need not have extracted figures
- Filing requirements, private-foundation filing requirements, affiliation, and group exemption number come from the IRS Business Master File. Empty-history guidance uses these codes without claiming why a particular filing is absent
- `filing_count` counts filings with extracted data; `filing_count_pdf_only` separately counts PDFs without financial extracts. Use `nonprofit_get_filings` for those links; PDF-only histories have no financial snapshot
- Data lags 1–2 years — `tax_prd_yr` in the snapshot is the fiscal year of the filing, not the current year
---
### `nonprofit_get_filings` tool
- All Form 990 filings with extracted data, sorted by full tax period newest first — per filing: revenue, expenses, assets, liabilities, net assets, revenue breakdown (contributions, program service, investment income), and the source PDF link
- Optional inclusive `from_year` / `to_year` bounds apply to both extracted and PDF-only histories. Totals remain unfiltered; an empty selected interval does not mean the organization has no history
- Financial fields follow each return's form type. For 990-PF, investment income is savings interest plus dividends and securities interest (Part I column (a), lines 3–4); both components must be extracted. It excludes capital gains, rents, and net investment income
- 990-PF filings include `grants_paid`, `distributable_amount`, `fair_market_value_assets`, and `net_investment_income`. The distributable amount is a payout requirement, not actual payments or a compliance measure
- `program_expense_ratio` is always `null` — ProPublica returns no Form 990 Part IX program-service expense total, so the program/management/fundraising split is only in the source PDF
- Form 990 includes other salaries and wages, payroll taxes, professional fundraising fees, and fundraising event gross, direct expenses, and net income. For 990-EZ, event gross is separate from combined gaming/fundraising expenses and net income; the combined figures cannot establish event-only results
- Executive compensation includes the source field for 990 and 990-PF. The 990-EZ extract has no compensation source: amount and field name are null, with guidance to Part IV of the PDF
- `filings_pdf_only` retains fiscal years and tax periods for returns without extracted data, including returns newer than the financial snapshots
- An EIN that resolves to a real org with no 990 on record returns an empty `filings` array plus a `notice`, not an error
- Data lags 1–2 years — always cite `tax_prd_yr` (fiscal year) when presenting figures
## Features
Built on [`@cyanheads/mcp-ts-core`](https://github.com/cyanheads/mcp-ts-core): stdio and Streamable HTTP transports, pluggable auth (`none` / `jwt` / `oauth`), swappable storage (`in-memory`, `filesystem`, `Supabase`, `Cloudflare KV/R2/D1`), structured logging with optional OpenTelemetry tracing.
ProPublica Nonprofit Explorer / IRS-specific:
- Keyless access — ProPublica Nonprofit Explorer API requires no API key
- Covers 1.8M+ IRS-recognized tax-exempt organizations
- IRS Form 990 data: annual filings for public charities (990), small orgs (990-EZ), and private foundations (990-PF)
- Source filing PDF link on every filing record, except where IRS PDF processing lags the extracted data and `pdf_url` is still null
- Data sourced from ProPublica Nonprofit Explorer, derived from IRS Form 990 filings; data lags 1–2 years
Agent-friendly output:
- Provenance on every response — `data_source` attribution on all tool outputs, ProPublica URL for direct verification
- Filing-year clarity — `tax_prd_yr` prominently labeled as fiscal year with explicit lag caveat in every financial response
- Null values are rendered, not dropped — the formatted text names why a value is absent (never recorded by the IRS, not extracted from the filing, not carried by that form type), and `structuredContent` keeps an explicit `null` rather than omitting the key
- Field-name transparency on compensation — `field_name` and `form_type` exposed so agents know exactly which IRS field was read
The published [nonprofit-explorer-guide](./skills/nonprofit-explorer-guide/SKILL.md) covers diligence, financial comparisons, and when to inspect the source return. It is included in npm, Docker, and desktop bundles and served through MCP skill resources.
## Getting started
### Public Hosted Instance
A public instance is available at `https://nonprofit-explorer.caseyjhand.com/mcp` — no installation required. Point any MCP client at it via Streamable HTTP, with this client config:
```json
{
"mcpServers": {
"nonprofit-explorer-mcp-server": {
"type": "streamable-http",
"url": "https://nonprofit-explorer.caseyjhand.com/mcp"
}
}
}
```
### Self-Hosted / Local
Add the following to your MCP client configuration file.
```json
{
"mcpServers": {
"nonprofit-explorer-mcp-server": {
"type": "stdio",
"command": "bunx",
"args": ["@cyanheads/nonprofit-explorer-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with npx (no Bun required):
```json
{
"mcpServers": {
"nonprofit-explorer-mcp-server": {
"type": "stdio",
"command": "npx",
"args": ["-y", "@cyanheads/nonprofit-explorer-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with Docker:
```json
{
"mcpServers": {
"nonprofit-explorer-mcp-server": {
"type": "stdio",
"command": "docker",
"args": [
"run", "-i", "--rm",
"-e", "MCP_TRANSPORT_TYPE=stdio",
"ghcr.io/cyanheads/nonprofit-explorer-mcp-server:latest"
]
}
}
}
```
For Streamable HTTP, set the transport and start the server:
```sh
MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp
```
### Prerequisites
- [Bun v1.4.0](https://bun.sh/) or higher (or Node.js v24+).
- No API key required — ProPublica Nonprofit Explorer is a keyless public API.
### Installation
1. **Clone the repository:**
```sh
git clone https://github.com/cyanheads/nonprofit-explorer-mcp-server.git
```
2. **Navigate into the directory:**
```sh
cd nonprofit-explorer-mcp-server
```
3. **Install dependencies:**
```sh
bun install
```
4. **Configure environment:**
```sh
cp .env.example .env
# edit .env as needed (no required vars — server works out of the box)
```
## Configuration
All configuration is validated at startup. Key environment variables:
| Variable | Description | Default |
|:---------|:------------|:--------|
| `MCP_TRANSPORT_TYPE` | Transport: `stdio` or `http` | `stdio` |
| `MCP_HTTP_PORT` | HTTP server port | `3010` |
| `MCP_HTTP_HOST` | HTTP server hostname | `127.0.0.1` |
| `MCP_HTTP_ENDPOINT_PATH` | HTTP endpoint path | `/mcp` |
| `MCP_PUBLIC_URL` | Public origin override for TLS-terminating reverse-proxy deployments | — |
| `MCP_AUTH_MODE` | Authentication: `none`, `jwt`, or `oauth` | `none` |
| `MCP_LOG_LEVEL` | Log level (`debug`, `info`, `warning`, `error`, etc.) | `info` |
| `LOGS_DIR` | Directory for log files (Node.js only) | `/logs` |
| `LOG_TOOL_FAILURE_PAYLOADS` | Log each failed tool call's arguments and result, redacted by key name and capped at `LOG_TOOL_FAILURE_PAYLOAD_MAX_BYTES` (default `16384`). A secret inside a free-form value is not redacted. | `false` |
| `STORAGE_PROVIDER_TYPE` | Storage backend: `in-memory`, `filesystem`, `supabase`, `cloudflare-kv/r2/d1` | `in-memory` |
| `OTEL_ENABLED` | Enable [OpenTelemetry instrumentation](https://github.com/cyanheads/mcp-ts-core/tree/main/docs/telemetry) | `false` |
No server-specific required variables. ProPublica Nonprofit Explorer is a keyless public API.
See [`.env.example`](./.env.example) for the full list of optional overrides.
## Running the server
### Local development
- **Build and run:**
```sh
# One-time build
bun run rebuild
# Run the built server
bun run start:stdio
# or
bun run start:http
```
- **Run checks and tests:**
```sh
bun run devcheck # Lint, format, typecheck, security
bun run test # Vitest test suite
bun run lint:mcp # Validate MCP definitions against spec
```
### Docker
```sh
docker build -t nonprofit-explorer-mcp-server .
docker run --rm -p 3010:3010 nonprofit-explorer-mcp-server
```
The Dockerfile defaults to HTTP transport, stateless session mode, and logs to `/var/log/nonprofit-explorer-mcp-server`. OpenTelemetry peer dependencies are installed by default — build with `--build-arg OTEL_ENABLED=false` to omit them.
## Project structure
| Directory | Purpose |
|:----------|:--------|
| `src/index.ts` | `createApp()` entry point — registers tools and inits the service. |
| `src/mcp-server/tools` | Tool definitions (`*.tool.ts`). Three tools for search and financial data. |
| `src/services/nonprofit-explorer` | ProPublica Nonprofit Explorer API client and domain types. |
| `skills/` | Published agent guidance for diligence and financial interpretation. |
| `tests/` | Unit and integration tests mirroring `src/`. |
## Development guide
See [`CLAUDE.md`/`AGENTS.md`](./CLAUDE.md) for development guidelines and architectural rules. The short version:
- Handlers throw, framework catches — no `try/catch` in tool logic
- Use `ctx.log` for request-scoped logging, `ctx.state` for tenant-scoped storage
- Register new tools via the arrays in `createApp()` in `src/index.ts`
- Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields
## Contributing
Issues are welcome. Run checks and tests before submitting:
```sh
bun run devcheck
bun run test
```
## License
Apache-2.0 — see [LICENSE](LICENSE) for details.