{"openapi":"3.1.0","info":{"title":"Free Small Biz Tools API","version":"1.0.0","description":"Free small-business calculators from freesmallbiztools.com: quote/estimate totals (tax, discount, deposit), late-fee calculator, and the site's free-tool directory as JSON. Paid (x402 USDC on Base): $0.01 late-fee reminder email (polite/firm/final), $0.05 good/better/best quote pack with terms, and a $1 small-business tool stack report built from the directory's checked listings. MCP server at /mcp. Invoicing and automatic reminders: PaidPilot (paidpilot.io).","contact":{"url":"https://api.freesmallbiztools.com/llms.txt"},"x-guidance":"Free small-business calculators from freesmallbiztools.com: quote/estimate totals (tax, discount, deposit), late-fee calculator, and the site's free-tool directory as JSON. Paid (x402 USDC on Base): $0.01 late-fee reminder email (polite/firm/final), $0.05 good/better/best quote pack with terms, and a $1 small-business tool stack report built from the directory's checked listings. MCP server at /mcp. Invoicing and automatic reminders: PaidPilot (paidpilot.io). Call a paid route without payment to get an x402 v2 challenge (402 + PAYMENT-REQUIRED header), pay in USDC, retry with PAYMENT-SIGNATURE. Invalid input -> 400, never charged. More: https://api.freesmallbiztools.com/llms.txt"},"servers":[{"url":"https://api.freesmallbiztools.com"}],"x-discovery":{"wellKnown":"https://api.freesmallbiztools.com/.well-known/x402","llms":"https://api.freesmallbiztools.com/llms.txt"},"paths":{"/v1/late-fee-notice":{"get":{"operationId":"v1_late_fee_notice","summary":"Late-fee reminder email for an overdue invoice","description":"Calculates the late fee and writes a ready-to-send reminder (subject + body) in a polite, firm or final tone. Bad input 400, never charged.","x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.01"},"protocols":[{"x402":{"version":2,"scheme":"exact","network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","payTo":"0x2dAF658B01e257206375798a15832E9f547D65dD"}}]},"responses":{"200":{"description":"Success (payment settled)","content":{"application/json":{}}},"400":{"description":"Invalid input. Never charged."},"402":{"description":"Payment required. x402 v2 challenge in the PAYMENT-REQUIRED header."},"404":{"description":"Unknown or deleted test. Never charged."},"409":{"description":"Report not ready (waiting, rejected_or_not_received, or analysis_failed). Never charged."}},"parameters":[{"name":"amount","in":"query","required":true,"schema":{"type":"string","description":"Invoice amount, e.g. 1200"},"example":"1200"},{"name":"due_date","in":"query","required":true,"schema":{"type":"string","description":"YYYY-MM-DD"},"example":"2026-09-01"},{"name":"paid_date","in":"query","required":false,"schema":{"type":"string","description":"YYYY-MM-DD (default today)"},"example":"2026-10-14"},{"name":"rate","in":"query","required":false,"schema":{"type":"string","description":"Rate number (default 1.5)"},"example":"1.5"},{"name":"rate_type","in":"query","required":false,"schema":{"type":"string","enum":["monthly_percent","annual_percent","daily_percent","flat"]},"example":"monthly_percent"},{"name":"grace_days","in":"query","required":false,"schema":{"type":"string"}},{"name":"tone","in":"query","required":false,"schema":{"type":"string","enum":["polite","firm","final"]},"example":"polite"},{"name":"client_name","in":"query","required":false,"schema":{"type":"string"}},{"name":"business_name","in":"query","required":false,"schema":{"type":"string"}},{"name":"invoice_number","in":"query","required":false,"schema":{"type":"string"}}]}},"/v1/quote-pack":{"post":{"operationId":"v1_quote_pack","summary":"Good / better / best quote pack with terms and a cover note","description":"From your line items: three priced options, deposit, validity date, standard terms and a short cover note. Bad input 400, never charged.","x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.05"},"protocols":[{"x402":{"version":2,"scheme":"exact","network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","payTo":"0x2dAF658B01e257206375798a15832E9f547D65dD"}}]},"responses":{"200":{"description":"Success (payment settled)","content":{"application/json":{}}},"400":{"description":"Invalid input. Never charged."},"402":{"description":"Payment required. x402 v2 challenge in the PAYMENT-REQUIRED header."},"404":{"description":"Unknown or deleted test. Never charged."},"409":{"description":"Report not ready (waiting, rejected_or_not_received, or analysis_failed). 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Bad input 400, never charged.","x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"1"},"protocols":[{"x402":{"version":2,"scheme":"exact","network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","payTo":"0x2dAF658B01e257206375798a15832E9f547D65dD"}}]},"responses":{"200":{"description":"Success (payment settled)","content":{"application/json":{}}},"400":{"description":"Invalid input. Never charged."},"402":{"description":"Payment required. x402 v2 challenge in the PAYMENT-REQUIRED header."},"404":{"description":"Unknown or deleted test. Never charged."},"409":{"description":"Report not ready (waiting, rejected_or_not_received, or analysis_failed). 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