Why This Exists

YNAB's budgeting philosophy works best when you interact with your budget frequently - but the app interface isn't designed for quick queries or bulk operations. "How much did I spend on groceries this month?" shouldn't require navigating three screens. "Categorize all my Amazon orders from this week" shouldn't be a manual, one-by-one process.

This server gives your AI assistant full access to YNAB's API, turning natural language into budget operations. All monetary values are automatically converted between dollars and YNAB's internal milliunits format so the AI never has to think about it. Built on the official YNAB JavaScript SDK with direct API calls for the newest endpoints (category creation, category groups, money movements) that the SDK hasn't caught up with yet.

Quick Start

Install with MCPB

For Claude Desktop and other MCPB-compatible clients, download the local bundle from the v1.4.0 release:

Download ynab-mcp-server-1.4.0.mcpb

The bundle includes the YNAB favicon, production runtime dependencies, and setup prompts for your personal access token and optional default budget ID.

1. Get a YNAB Personal Access Token

Go to YNAB Developer Settings and create a new personal access token.

2. Configure your MCP client

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "ynab": {
      "command": "npx",
      "args": ["-y", "@oliverames/ynab-mcp-server"],
      "env": {
        "YNAB_API_TOKEN": "your-token-here"
      }
    }
  }
}

Claude Code (.mcp.json):

{
  "mcpServers": {
    "ynab": {
      "command": "npx",
      "args": ["-y", "@oliverames/ynab-mcp-server"],
      "env": {
        "YNAB_API_TOKEN": "your-token-here"
      }
    }
  }
}

Or install globally and point to the binary directly:

npm install -g @oliverames/ynab-mcp-server

{
  "mcpServers": {
    "ynab": {
      "command": "ynab-mcp-server",
      "env": {
        "YNAB_API_TOKEN": "your-token-here",
        "YNAB_BUDGET_ID": "optional-default-budget-id"
      }
    }
  }
}

That's it. Your AI can now talk to YNAB.

What You Can Do

| Ask your AI... | What happens under the hood | |---|---| | "How much did I spend on groceries this month?" | search_categories → get_month_category | | "Show me all unapproved transactions" | review_unapproved groups by readiness | | "Log a $50 Costco trip under groceries" | search_payees → search_categories → create_transaction | | "Set up monthly $1,500 rent on the 1st" | create_scheduled_transaction with monthly frequency | | "Move $200 from emergency fund to dining" | search_categories → update_month_category (x2) | | "Categorize all my Amazon orders from this week" | get_transactions (filtered) → update_transactions (batch) | | "Create a 'Side Projects' spending category" | search_categories (find group) → create_category | | "How has my budget been re-allocated this month?" | get_money_movements_by_month | | "What recurring payments do I have?" | list_scheduled_transactions | | "Import my latest bank transactions" | import_transactions triggers linked account sync |

Features

Complete YNAB API v1.83 coverage with 44 tools:

| Resource | Tools | Capabilities | |----------|-------|-------------| | Budgets | 4 | List, view details, settings | | Accounts | 3 | List, view, create | | Categories | 9 | Full CRUD, groups, search, goals, monthly budgets | | Payees | 5 | List, view, create, rename, search | | Payee Locations | 3 | GPS coordinates for mobile transactions | | Months | 2 | Monthly summaries with per-category breakdown | | Money Movements | 4 | Budget re-allocation tracking | | Transactions | 8 | Full CRUD, bulk ops, split transactions, multi-filter | | Scheduled Transactions | 5 | Full CRUD for recurring transactions | | Convenience | 1 | Unapproved transaction review workflow |

Design Decisions

• Dollar amounts everywhere - inputs and outputs are in dollars (-12.34), never milliunits (-12340). Conversion is automatic and transparent.
• Smart budget resolution - set YNAB_BUDGET_ID for a default, or omit it to auto-resolve to your last-used budget. Every tool accepts an optional budgetId override.
• Split transactions - first-class support for subtransactions in create, read, and format operations.
• Bulk operations - create_transactions and update_transactions handle arrays in a single API call.
• Fetch-then-merge updates - scheduled transaction updates (which use PUT semantics) automatically fetch the current state and merge your changes, so you only specify what changed.
• Fuzzy search - search_categories and search_payees do case-insensitive partial matching across all entries.
• Approval workflow with anomaly flags - review_unapproved groups transactions into "ready to approve" (categorized, split, or transfer) and "needs attention" (uncategorized), and attaches a flags array to each transaction surfacing anomalies: manually_entered (not bank-imported), match_broken (stale match reference), scheduled_transaction_realized, new_payee, no_prior_amount_match (novel amount for this payee), and category_drift:was_X (payee categorized differently in the prior 60 days). Group-level flags aggregate the union of all transaction flags.
• Nullable updates - update tools accept null for clearable fields (memo, payeeName, categoryId, flagColor) to distinguish "don't change" (omit) from "clear this field" (null).
• Target behavior support - category create/update tools expose goalNeedsWholeAmount for YNAB's "Set aside another" vs. "Refill up to" goal behavior.
• Delta request support - high-volume list tools accept lastKnowledgeOfServer and return server_knowledge when that parameter is provided.
• Debt account support - loan and debt accounts include debt_original_balance, debt_interest_rates, debt_minimum_payments, and debt_escrow_amounts with correct unit conversion (rates stay as percentages, payments convert from milliunits).

Tools Reference

User & Budgets

| Tool | Description | |------|-------------| | get_user | Get the authenticated user | | list_budgets | List all budgets with IDs, names, date ranges, format settings, and default budget | | get_budget | Get budget summary (name, currency, account/category/payee counts) | | get_budget_settings | Get currency and date format settings |

Accounts

| Tool | Description | |------|-------------| | list_accounts | List all accounts with balances, debt details, and import status | | get_account | Get full account details including notes and debt fields | | create_account | Create a new account (checking, savings, creditCard, mortgage, etc.) |

Supported account types: checking, savings, cash, creditCard, lineOfCredit, otherAsset, otherLiability, mortgage, autoLoan, studentLoan, personalLoan, medicalDebt, otherDebt

Categories & Category Groups

| Tool | Description | |------|-------------| | list_categories | List all category groups and their categories with budgeted/activity/balance | | get_category | Get full category details including goal progress and cadence | | get_month_category | Get category budget for a specific month | | update_month_category | Set the budgeted amount for a category in a month | | update_category | Update name, note, goal target, goal target date, or move to a different group | | create_category | Create a new category in an existing group (with optional goal) | | create_category_group | Create a new category group | | update_category_group | Rename a category group | | search_categories | Case-insensitive partial name search (e.g., "groc" finds "Groceries") |

Payees

| Tool | Description | |------|-------------| | list_payees | List all payees with transfer account mappings | | get_payee | Get payee details | | create_payee | Create a new payee | | update_payee | Rename a payee | | search_payees | Case-insensitive partial name search |

Payee Locations

| Tool | Description | |------|-------------| | list_payee_locations | List all payee locations (GPS coordinates from mobile app) | | get_payee_location | Get a specific payee location | | get_payee_locations_by_payee | Get all locations for a specific payee |

Months

| Tool | Description | |------|-------------| | list_months | List budget months with income, budgeted, activity, to-be-budgeted, age of money, and notes | | get_month | Get month detail with per-category budget/activity/balance/goal breakdown |

Money Movements

| Tool | Description | |------|-------------| | list_money_movements | List all money movements (budget re-allocations between categories) | | get_money_movements_by_month | Get money movements for a specific month | | list_money_movement_groups | List all money movement groups (batched re-allocations) | | get_money_movement_groups_by_month | Get money movement groups for a specific month |

Transactions

| Tool | Description | |------|-------------| | get_transactions | Get transactions with filters: by account, category, payee, month, or status (unapproved/uncategorized) | | get_transaction | Get a single transaction by ID (includes subtransactions). Auto-handles composite scheduled-transaction IDs like uuid_YYYY-MM-DD. | | create_transaction | Create a transaction with optional split (subtransactions must sum to total) | | create_transactions | Bulk create multiple transactions in a single API call (supports split transactions) | | update_transaction | Partial update - only specified fields change | | update_transactions | Batch update multiple transactions at once | | delete_transaction | Delete a transaction | | import_transactions | Trigger import from linked bank accounts |

Scheduled Transactions

| Tool | Description | |------|-------------| | list_scheduled_transactions | List all recurring transactions | | get_scheduled_transaction | Get a specific scheduled transaction | | create_scheduled_transaction | Create a recurring transaction with frequency | | update_scheduled_transaction | Update (fetch-then-merge preserves unchanged fields) | | delete_scheduled_transaction | Delete a scheduled transaction |

Supported frequencies: never, daily, weekly, everyOtherWeek, twiceAMonth, every4Weeks, monthly, everyOtherMonth, every3Months, every4Months, twiceAYear, yearly, everyOtherYear

Convenience

| Tool | Description | |------|-------------| | review_unapproved | Get unapproved transactions grouped by readiness: "ready to approve" (categorized, split, or transfer) vs. "needs category first" (uncategorized). Each transaction includes a flags array highlighting anomalies (manually_entered, match_broken, no_prior_amount_match, category_drift, new_payee, scheduled_transaction_realized) computed against 60 days of payee history. Includes a warning against blind approval. |

Environment Variables

| Variable | Required | Description | |----------|----------|-------------| | YNAB_API_TOKEN | Yes* | Personal access token from YNAB Developer Settings | | YNAB_BUDGET_ID | No | Default budget ID. If omitted, uses "last-used" (your most recently accessed budget). Run list_budgets to find IDs. | | YNAB_OP_PATH | No | 1Password secret reference for your API token (see below). Required only if using the 1Password fallback instead of YNAB_API_TOKEN. |

*YNAB_API_TOKEN is required unless YNAB_OP_PATH is set.

1Password Integration

If you store your YNAB token in 1Password CLI, set YNAB_OP_PATH to your secret reference and omit YNAB_API_TOKEN:

{
  "mcpServers": {
    "ynab": {
      "command": "npx",
      "args": ["-y", "@oliverames/ynab-mcp-server"],
      "env": {
        "YNAB_OP_PATH": "op://Personal/YNAB API Token/credential"
      }
    }
  }
}

The fallback adds ~1-2s to startup and is silently skipped if op is unavailable or the item is not found.

Amount Handling

All amounts in tool inputs and outputs are in dollars (e.g., -12.34 for a $12.34 outflow). The server converts to/from YNAB's internal milliunits format automatically.

| Direction | Sign | Example | |-----------|------|---------| | Outflow (spending) | Negative | -50.00 | | Inflow (income) | Positive | 2500.00 | | Transfer out | Negative | -1000.00 | | Transfer in | Positive | 1000.00 |

Rate Limiting

The YNAB API allows 200 requests per hour per access token, enforced on a rolling window. Each tool call typically uses one API request (except update_scheduled_transaction which uses two - a GET to fetch current state, then a PUT to merge changes). The server surfaces rate limit errors as standard MCP error responses.

Architecture

┌─────────────────────┐     ┌──────────────────┐     ┌──────────────┐
│  AI Assistant       │────▶│  YNAB MCP Server │────▶│  YNAB API    │
│  (Claude, GPT, etc) │◀────│  (this package)  │◀────│  api.ynab.com│
└─────────────────────┘     └──────────────────┘     └──────────────┘
         MCP                    stdio transport           HTTPS/REST

• Transport: stdio (standard MCP server pattern)
• Auth: Bearer token via YNAB_API_TOKEN environment variable
• SDK: Official ynab v2.5+ for core endpoints, direct fetch for newer API features
• Validation: All parameters validated with Zod schemas
• Error handling: API errors are caught, formatted, and returned as MCP error responses with detail messages

Testing

The integration test suite runs against a live YNAB budget. Most write tests create temporary transactions and delete or restore them, but category and category group creation is not reversible through the public API and is skipped unless explicitly enabled.

YNAB_API_TOKEN=your-token YNAB_BUDGET_ID=your-budget-id npm test

Use YNAB_TEST_BUDGET_ID to target a dedicated test budget without changing your server default. To include category and category group creation coverage, run with YNAB_RUN_NONREVERSIBLE_TESTS=1.

Tests cover all tool categories: reads, reversible writes, bulk operations, search, split transactions, scheduled transaction CRUD with fetch-then-merge verification, money movements, and payee locations.

Development

git clone https://github.com/oliverames/ynab-mcp-server.git
cd ynab-mcp-server
npm install
YNAB_API_TOKEN=your-token npm start

Dependencies

• @modelcontextprotocol/sdk - MCP server framework
• ynab - Official YNAB JavaScript client

Zero additional dependencies. No build step. Pure ESM.

License

MIT