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$ your household's financial brain

Your money, in the AI you use.

One URL into ChatGPT, Claude, Cursor, or any MCP client — or a REST API with a revocable key. Real transactions, receipts, budgets, and net worth. Read-only, scoped to your account, OAuth sign-in. No key to paste into a prompt.

Connect ChatGPT or ClaudeExplore focuses and coaching styles

session — agent calling FYN

you → How much did I spend on food this month?
> POST /v1/agent/spending/breakdown {"group_by":"category","start_date":"2026-03-01"}
fyn → $529.68 this month — $342.18 groceries, $187.50 dining out. Dining is up 23% MoM.
> GET /v1/agent/insights/health
fyn → 72/100 (B). Savings rate 12%; subscriptions $127/mo. Top cut: unused streaming services.

$ financial context, maintained between conversations

Start with the finance work already in place.

Bank connectivity gives an agent account data. FYN adds saved financial records and ongoing analysis: automatic budgets, receipt line items, and daily checks for changes worth your attention.

Ask about the purchase

Search itemized receipts and their prices, then connect that detail to your broader spending history.

Read a budget that keeps up

FYN maintains automatic budgets from recent spending and checks for budget pressure and subscription increases.

Reuse the same context

Query saved records from compatible assistants or your own workflows. You can revoke access at any time.

FYN handles its scheduled finance checks; your connected agent chooses when to query them. Connected agents can read your data, but cannot change budgets or move money through this API. Bank sync and advanced receipt tools require Pro.

Compare FYN and Grok Bot

Pro

One financial brain. Specialists for everyday life.

Pair one coaching style with the focuses that matter to your household, using the same financial facts. These six focuses and five styles are included with Pro.

Pro

Prices

Track price changes in the things you buy and find the lowest prices in your own receipt history.

Pro

Debt

See what card interest costs you and compare payoff priorities, including the tradeoff between clearing smaller balances and paying the costliest card first.

Pro

Dining & habits

Spot the habits that change your budget, from coffee runs to takeout nights. Compare how much and how often you spend with your own usual patterns.

Pro

Splurge & travel

See room for a chosen splurge in your budget and review recorded in-person spending from past trips.

Pro

Grocery & meals

See which staples you tend to rebuy, when they may be due, and where you have bought them for less.

Pro

Cost of living

Estimate what your usual month could cost in another city or state, using your spending mix and 2024 regional price data. Taxes and homeownership costs are not modeled.

Meal guides, detailed debt payoff plans, and investment recommendations remain on the roadmap.

Five coaching styles

Your priorities. Your kind of coach.

A focus sets what FYN watches. A coaching style shapes the strategy and tone. Household owners choose one style and any combination of focuses in settings. Chat uses saved choices right away. Insights update on the next daily run.

Balanced
A practical mix of spending, saving, and debt priorities, with a direct, everyday tone.
Debt snowball
Card debt first, smaller balances for momentum, and clear interest tradeoffs.
Builder
Income changes, cash flow, and saving more, with an energetic voice.
Saver / FIRE
Savings rate, cash reserves, and net worth trends, with a calm, long-term perspective.
Conscious spender
Room for spending you value, with budgets and subscriptions in view and a warm tone.

Pro

Follow-up on charges

FYN asks about possible duplicate charges and subscription price increases, with letters you review and send yourself. It remembers your response and tracks a disputed charge for a matching refund.

In development

Spend Guard

Planned household budget checks and owner approvals would give connected agents guidance before spending, with a shared record of requests and decisions. This would be advisory: it would not block bank charges or move money.

Spend Guard is not publicly available.

for machines — machine-readable discovery

fyn.fyi/llms.txt — short site + API index for LLMs
fyn.fyi/llms-full.txt — full endpoint reference, params, limits
raw.githubusercontent.com/fynfyi/agent-skill/main/SKILL.md — installable agent skill
api.fyn.fyi/.well-known/oauth-protected-resource · oauth-authorization-server — self-discovering MCP clients

mcp — one endpoint, OAuth 2.1, read-only

https://api.fyn.fyi/v1/mcp

Sign in with your real FYN account via OAuth 2.1 + PKCE — no API key, no credentials shared with the model. Read-only scopes, revocable anytime in Settings → Agent access.

ChatGPT

  1. 01Open chatgpt.com/plugins, select +, then Add custom MCP server.
  2. 02Name it FYN, paste https://api.fyn.fyi/v1/mcp as the server URL, accept the warning and select Create as a plugin.
  3. 03Sign in to FYN when asked and select Allow. In a new chat, type @ and pick FYN.

Claude

  1. 01Open Customize → Connectors, select + Add, then Add custom connector.
  2. 02Name it FYN, paste https://api.fyn.fyi/v1/mcp and select Add.
  3. 03Sign in to FYN when asked and select Allow.

Claude Code, Cursor and other desktop tools: create a key in Settings → Agent access and send it as a header.

claude code

claude mcp add --transport http fyn https://api.fyn.fyi/v1/mcp --header "Authorization: Bearer fyn_ak_…"

cursor — ~/.cursor/mcp.json

{
  "mcpServers": {
    "fyn": {
      "url": "https://api.fyn.fyi/v1/mcp",
      "headers": { "Authorization": "Bearer fyn_ak_…" }
    }
  }
}

what it can answer

  • ·“What else did I buy at Costco last month?”
  • ·“How much am I spending on subscriptions?”
  • ·“Am I over budget on dining this month?”
  • ·“What’s my net worth and savings rate?”
  • ·“Search my receipts for laptop.”

auth model

  • ·OAuth 2.1 + PKCE, dynamic client registration
  • ·scopes are read-only — agents can’t move money
  • ·bank access via Plaid is read-only
  • ·authorization revocable instantly
  • ·tokens scoped to one FYN account

$ > rest — api key, for non-MCP agents

Setup

  1. 01Sign up at fyn.fyi — free tier, no card. On Pro, connect your bank via Plaid (read-only); sync usually takes under 60s. Not needed for the MCP flow above.
  2. 02Settings → Agent Access → New Key. The key is shown once.
  3. 03Point your agent at it:

env

export FYN_API_KEY=fyn_ak_…

Verify with a single call:

curl — verify key

$ curl -s https://api.fyn.fyi/v1/agent/accounts/net-worth \
-H "Authorization: Bearer $FYN_API_KEY" | jq .

response

{
  "success": true,
  "data": { "net_worth": 47250.83, "assets": 52100.00, "liabilities": 4849.17, "accounts": 4 },
  "meta": { "plan": "free", "rateLimit": { "remaining": 499, "limit": 500 } }
}

Prefer an installable skill?mkdir -p ~/.claude/skills/fyn-finance && curl -sL https://raw.githubusercontent.com/fynfyi/agent-skill/main/SKILL.md -o ~/.claude/skills/fyn-finance/SKILL.md— works with Claude Code and any Agent Skills compatible tool.

$ > endpoints — 25 read-only data · 4 key management

One key, everything below.

transactions

GET/v1/agent/transactions/recentrecent transactions, filterable by merchant / category / date
POST/v1/agent/transactions/sumtotal spend for a period / merchant / category

spending

POST/v1/agent/spending/breakdownspend by category or merchant
POST/v1/agent/spending/comparemonth-over-month comparison
POST/v1/agent/spending/discretionarydiscretionary vs committed spend

accounts

GET/v1/agent/accounts/net-worthassets, liabilities, net worth
GET/v1/agent/accounts/balancesall accounts
GET/v1/agent/accounts/balancesingle account

budgets · subscriptions · cash flow

GET/v1/agent/budget/statusper-category budget usage
GET/v1/agent/budget/overover-budget categories
GET/v1/agent/subscriptionsrecurring charges
GET/v1/agent/subscriptions/totalmonthly subscription cost
GET/v1/agent/cashflowincome vs expenses
GET/v1/agent/cashflow/savings-ratesavings rate

insights

GET/v1/agent/insights/dailydaily briefing
GET/v1/agent/insights/weeklyweekly recap
GET/v1/agent/insights/alertsspending alerts
GET/v1/agent/insights/healthhealth score + recommendations
GET/v1/agent/insights/opportunitiessaving opportunities
POST/v1/agent/insights/asknatural-language question about your finances

portfolio

GET/v1/agent/portfolioportfolio value + allocation
GET/v1/agent/holdingsindividual holdings

receipts

POST/v1/agent/receipts/searchsearch receipts + line items
POST/v1/agent/receipts/ragRAG chat over receipts

intelligence

POST/v1/agent/affordabilitycan I afford this purchase?

Full reference — params, request / response examples

rate limits

free500 calls / 50 RAG requests per day
pro $9.99/mounlimited calls / 500 RAG requests per day

Every response carries meta.rateLimit so agents can back off before 429s.

security

  • ·keys hashed at rest (SHA-256), plaintext shown once, revocable instantly
  • ·read-only bank access via Plaid — FYN never moves money
  • ·all data scoped to the authorized account
  • ·HTTPS everywhere; MCP auth is OAuth 2.1 + PKCE

Connect your agent.

Free tier: 500 calls a day, no card.

Get started freeagent-skill on GitHub

works with any mcp client — chatgpt · claude · cursor · gemini cli · goose · roo code · raw http