{ "openapi": "3.1.0", "info": { "title": "FabTally Utility Belt — deterministic micro-utilities for agents", "version": "1.0.0", "description": "A bundle of fast, deterministic micro-utilities AI agents call constantly — timezone/DST, cron, iCal RRULE, unit & live currency conversion, safe regex, text diff, JSON-Schema validation, hashing/encoding/IDs, and business-day date math. Six utilities are FREE and unlimited; seven are $0.001/call via x402 (USDC on Base) or a prepaid credit key, each with a rate-limited free teaser. Stateless, no storage, sub-100ms, bad-input never charged. Also available as a standalone MCP server.", "x-guidance": "Free unlimited: POST /v1/convert, /v1/text, /v1/hash, /v1/encode, /v1/id, /v1/regex. Paid $0.001 (x402 USDC on Base, or prepaid X-FabTally-Key): POST /v1/timezone, /v1/cron, /v1/rrule, /v1/currency, /v1/diff, /v1/jsonschema, /v1/datemath — each has a rate-limited /free teaser. Unpaid paid-calls return an x402 402 challenge; pay and retry with the X-PAYMENT header. Bad input -> 400, never charged.", "contact": { "email": "hello@fabtally.com" } }, "servers": [ { "url": "https://belt.fabtally.com" } ], "paths": { "/agent/overview": { "get": { "operationId": "overview", "summary": "Capabilities, pricing, payment info (free)", "tags": [ "Discovery" ], "security": [], "responses": { "200": { "description": "Overview" } } } }, "/health": { "get": { "operationId": "health", "summary": "Health (free)", "tags": [ "Discovery" ], "security": [], "responses": { "200": { "description": "OK" } } } }, "/v1/convert": { "post": { "operationId": "convert", "summary": "convert (free)", "tags": [ "Free" ], "security": [], "description": "Unit conversion across length, mass, temperature, volume, data, time, area, speed, angle, pressure, energy.", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "value": 100, "from": "c", "to": "f" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input" } } } }, "/v1/text": { "post": { "operationId": "text", "summary": "text (free)", "tags": [ "Free" ], "security": [], "description": "slugify, case-convert (camel/pascal/snake/kebab/constant/dot/path/title/sentence/upper/lower) and {{template}} fill.", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "op": "slugify", "text": "Héllo, World!" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input" } } } }, "/v1/hash": { "post": { "operationId": "hash", "summary": "hash (free)", "tags": [ "Free" ], "security": [], "description": "sha256/sha512/sha384/sha1/md5/sha3-256/keccak256/ripemd160, optional HMAC, hex/base64 output.", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "algorithm": "sha256", "text": "hello" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input" } } } }, "/v1/encode": { "post": { "operationId": "encode", "summary": "encode (free)", "tags": [ "Free" ], "security": [], "description": "base64 / base64url / hex / url / html encode & decode.", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "op": "base64-encode", "text": "hello" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input" } } } }, "/v1/id": { "post": { "operationId": "id", "summary": "id (free)", "tags": [ "Free" ], "security": [], "description": "Generate uuid v4/v7, ULID, nanoid, or random hex/base64url/int (count up to 1000).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "kind": "uuidv7", "count": 2 } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input" } } } }, "/v1/regex": { "post": { "operationId": "regex", "summary": "regex (free)", "tags": [ "Free" ], "security": [], "description": "test/match/extract/replace with catastrophic-backtracking protection (runs in a killable worker with a hard timeout).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "pattern": "(\\d+)", "flags": "g", "input": "a12 b34", "op": "extract" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input" } } } }, "/v1/timezone": { "post": { "operationId": "timezone", "summary": "timezone (paid, $0.001 USDC on Base)", "tags": [ "Paid" ], "description": "Convert an instant between IANA time zones with historically-correct DST. Give a datetime (ISO 8601 or epoch) + from_zone + to_zone; get the converted datetime, UTC offsets, tz abbreviations, DST flags, and the offset difference. Deterministic, sub-100ms, no storage.", "x-payment-info": { "price": { "mode": "fixed", "currency": "USD", "amount": "0.001000" }, "protocols": [ { "x402": { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "maxAmountRequired": "1000", "payTo": "0xccB5d25C698FdfdaA7B21d54088774cF512A90e3", "resource": "https://belt.fabtally.com/v1/timezone", "facilitator": "https://facilitator.daydreams.systems", "maxTimeoutSeconds": 60 } } ] }, "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "datetime": "2021-03-14T01:30:00", "from_zone": "America/New_York", "to_zone": "Europe/London" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input (never charged)" }, "402": { "description": "Payment Required (x402 v2 challenge)" } } } }, "/v1/timezone/free": { "post": { "operationId": "timezone_free", "summary": "timezone — rate-limited free teaser", "tags": [ "Free" ], "security": [], "description": "Free teaser for timezone (daily per-IP quota).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "datetime": "2021-03-14T01:30:00", "from_zone": "America/New_York", "to_zone": "Europe/London" } } } }, "responses": { "200": { "description": "Teaser result" }, "429": { "description": "Free daily quota exceeded" } } } }, "/v1/cron": { "post": { "operationId": "cron", "summary": "cron (paid, $0.001 USDC on Base)", "tags": [ "Paid" ], "description": "Parse a cron expression and return the next N run times plus a plain-English description. Give a 5- or 6-field cron `expression` (+ optional IANA `timezone`, `count`, `from`). Deterministic.", "x-payment-info": { "price": { "mode": "fixed", "currency": "USD", "amount": "0.001000" }, "protocols": [ { "x402": { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "maxAmountRequired": "1000", "payTo": "0xccB5d25C698FdfdaA7B21d54088774cF512A90e3", "resource": "https://belt.fabtally.com/v1/cron", "facilitator": "https://facilitator.daydreams.systems", "maxTimeoutSeconds": 60 } } ] }, "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "expression": "0 9 * * 1-5", "timezone": "UTC", "count": 5 } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input (never charged)" }, "402": { "description": "Payment Required (x402 v2 challenge)" } } } }, "/v1/cron/free": { "post": { "operationId": "cron_free", "summary": "cron — rate-limited free teaser", "tags": [ "Free" ], "security": [], "description": "Free teaser for cron (daily per-IP quota).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "expression": "0 9 * * 1-5", "timezone": "UTC", "count": 5 } } } }, "responses": { "200": { "description": "Teaser result" }, "429": { "description": "Free daily quota exceeded" } } } }, "/v1/rrule": { "post": { "operationId": "rrule", "summary": "rrule (paid, $0.001 USDC on Base)", "tags": [ "Paid" ], "description": "Expand an iCal RRULE recurrence into its next N occurrences. Give an `rrule` string (RFC 5545, e.g. FREQ=WEEKLY;BYDAY=MO,WE;COUNT=10) + optional `after`, `count`, `timezone`.", "x-payment-info": { "price": { "mode": "fixed", "currency": "USD", "amount": "0.001000" }, "protocols": [ { "x402": { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "maxAmountRequired": "1000", "payTo": "0xccB5d25C698FdfdaA7B21d54088774cF512A90e3", "resource": "https://belt.fabtally.com/v1/rrule", "facilitator": "https://facilitator.daydreams.systems", "maxTimeoutSeconds": 60 } } ] }, "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "rrule": "FREQ=WEEKLY;BYDAY=MO,WE;COUNT=10", "count": 5 } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input (never charged)" }, "402": { "description": "Payment Required (x402 v2 challenge)" } } } }, "/v1/rrule/free": { "post": { "operationId": "rrule_free", "summary": "rrule — rate-limited free teaser", "tags": [ "Free" ], "security": [], "description": "Free teaser for rrule (daily per-IP quota).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "rrule": "FREQ=WEEKLY;BYDAY=MO,WE;COUNT=10", "count": 5 } } } }, "responses": { "200": { "description": "Teaser result" }, "429": { "description": "Free daily quota exceeded" } } } }, "/v1/currency": { "post": { "operationId": "currency", "summary": "currency (paid, $0.001 USDC on Base)", "tags": [ "Paid" ], "description": "Live currency conversion at reference/mid-market rates from a keyless public central-bank feed (ECB), cached in-memory. Give `amount` + `from` + `to` ISO-4217 codes. Informational, not a dealable quote.", "x-payment-info": { "price": { "mode": "fixed", "currency": "USD", "amount": "0.001000" }, "protocols": [ { "x402": { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "maxAmountRequired": "1000", "payTo": "0xccB5d25C698FdfdaA7B21d54088774cF512A90e3", "resource": "https://belt.fabtally.com/v1/currency", "facilitator": "https://facilitator.daydreams.systems", "maxTimeoutSeconds": 60 } } ] }, "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "amount": 100, "from": "USD", "to": "EUR" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input (never charged)" }, "402": { "description": "Payment Required (x402 v2 challenge)" } } } }, "/v1/currency/free": { "post": { "operationId": "currency_free", "summary": "currency — rate-limited free teaser", "tags": [ "Free" ], "security": [], "description": "Free teaser for currency (daily per-IP quota).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "amount": 100, "from": "USD", "to": "EUR" } } } }, "responses": { "200": { "description": "Teaser result" }, "429": { "description": "Free daily quota exceeded" } } } }, "/v1/diff": { "post": { "operationId": "diff", "summary": "diff (paid, $0.001 USDC on Base)", "tags": [ "Paid" ], "description": "Text diff: a unified patch plus a structured op-list (add/remove/equal) and add/remove/hunk stats. Give `a` + `b` (+ optional `mode` lines|words|chars, `context`, labels). Deterministic.", "x-payment-info": { "price": { "mode": "fixed", "currency": "USD", "amount": "0.001000" }, "protocols": [ { "x402": { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "maxAmountRequired": "1000", "payTo": "0xccB5d25C698FdfdaA7B21d54088774cF512A90e3", "resource": "https://belt.fabtally.com/v1/diff", "facilitator": "https://facilitator.daydreams.systems", "maxTimeoutSeconds": 60 } } ] }, "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "a": "line1\nline2\n", "b": "line1\nline2 changed\n" } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input (never charged)" }, "402": { "description": "Payment Required (x402 v2 challenge)" } } } }, "/v1/diff/free": { "post": { "operationId": "diff_free", "summary": "diff — rate-limited free teaser", "tags": [ "Free" ], "security": [], "description": "Free teaser for diff (daily per-IP quota).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "a": "line1\nline2\n", "b": "line1\nline2 changed\n" } } } }, "responses": { "200": { "description": "Teaser result" }, "429": { "description": "Free daily quota exceeded" } } } }, "/v1/jsonschema": { "post": { "operationId": "jsonschema", "summary": "jsonschema (paid, $0.001 USDC on Base)", "tags": [ "Paid" ], "description": "Validate a value against a JSON Schema (draft 2020-12) and explain every error in plain English (which property, what was wrong, allowed values). Give `schema` + `data`.", "x-payment-info": { "price": { "mode": "fixed", "currency": "USD", "amount": "0.001000" }, "protocols": [ { "x402": { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "maxAmountRequired": "1000", "payTo": "0xccB5d25C698FdfdaA7B21d54088774cF512A90e3", "resource": "https://belt.fabtally.com/v1/jsonschema", "facilitator": "https://facilitator.daydreams.systems", "maxTimeoutSeconds": 60 } } ] }, "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "schema": { "type": "object", "required": [ "x" ], "properties": { "x": { "type": "integer" } } }, "data": { "x": "nope" } } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input (never charged)" }, "402": { "description": "Payment Required (x402 v2 challenge)" } } } }, "/v1/jsonschema/free": { "post": { "operationId": "jsonschema_free", "summary": "jsonschema — rate-limited free teaser", "tags": [ "Free" ], "security": [], "description": "Free teaser for jsonschema (daily per-IP quota).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "schema": { "type": "object", "required": [ "x" ], "properties": { "x": { "type": "integer" } } }, "data": { "x": "nope" } } } } }, "responses": { "200": { "description": "Teaser result" }, "429": { "description": "Free daily quota exceeded" } } } }, "/v1/datemath": { "post": { "operationId": "datemath", "summary": "datemath (paid, $0.001 USDC on Base)", "tags": [ "Paid" ], "description": "Calendar date math: add/subtract an ISO-8601 duration, diff two datetimes into chosen units, or add/diff business days (configurable weekend + holiday list). Give `op` + the relevant fields.", "x-payment-info": { "price": { "mode": "fixed", "currency": "USD", "amount": "0.001000" }, "protocols": [ { "x402": { "scheme": "exact", "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "maxAmountRequired": "1000", "payTo": "0xccB5d25C698FdfdaA7B21d54088774cF512A90e3", "resource": "https://belt.fabtally.com/v1/datemath", "facilitator": "https://facilitator.daydreams.systems", "maxTimeoutSeconds": 60 } } ] }, "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "op": "business-add", "date": "2026-07-31", "days": 3 } } } }, "responses": { "200": { "description": "Result", "content": { "application/json": { "schema": { "type": "object" } } } }, "400": { "description": "Bad input (never charged)" }, "402": { "description": "Payment Required (x402 v2 challenge)" } } } }, "/v1/datemath/free": { "post": { "operationId": "datemath_free", "summary": "datemath — rate-limited free teaser", "tags": [ "Free" ], "security": [], "description": "Free teaser for datemath (daily per-IP quota).", "requestBody": { "required": true, "content": { "application/json": { "schema": { "type": "object" }, "example": { "op": "business-add", "date": "2026-07-31", "days": 3 } } } }, "responses": { "200": { "description": "Teaser result" }, "429": { "description": "Free daily quota exceeded" } } } } } }