{"uid":"cap_85_MK0qxFX0ELftNNxiEI","slug":"fastsend-sms-email-messaging-api-262c1939","name":"Fastsend SMS & Email Messaging API","description":"Send an SMS or email message via Fastsend.","url":"https://fastsend.dev/api/messages","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"to":{"type":"string"},"from":{"type":"string"},"channel":{"enum":["sms","email"],"type":"string"},"content":{"type":"string"},"subject":{"type":"string"}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.165","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.165/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.165","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.165","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_uWTq4tmLXih1LMxy2ayb9","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.165","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Send an SMS text message or email to a recipient via the Fastsend messaging platform.","exampleAgentPrompt":"Send an SMS via Fastsend to +12125550199 from +18005550100 saying 'Your order #4821 has shipped and will arrive by Friday.'","exampleUseCases":[{"title":"Order shipment SMS alert","prompt":"Send a text message to +12125550199 from +18005550100 letting them know their order #4821 has shipped and will arrive by Friday."},{"title":"Transactional email with subject","prompt":"Send an email to jane.doe@example.com from noreply@myapp.com with the subject 'Password Reset Request' and the body 'Click here to reset your password: https://myapp.com/reset/abc123'."},{"title":"Agent-triggered user notification","prompt":"Alert user at +14155550172 via SMS from +18005550100 that their appointment is confirmed for tomorrow at 3pm — just a short text saying 'Your appointment is confirmed for tomorrow at 3:00 PM. See you then!'"}],"resultDescription":"A confirmation response indicating whether the SMS or email message was successfully dispatched by Fastsend, typically including delivery status or a message ID.","failureModes":["Invalid or unformatted phone number for SMS channel","Invalid email address format","Missing required fields (to, from, channel, content)","Insufficient USDC balance to cover $0.165 per-call cost","Unsupported channel value (not 'sms' or 'email')","Missing subject field when channel is email","Payment failure via x402 protocol"],"whenToPreferThis":"Choose this endpoint when an AI agent needs to programmatically send a single SMS or email notification and can pay per-message in USDC via the x402 protocol. It is well-suited for transactional alerts, confirmations, or one-off notifications where no existing messaging infrastructure is in place. Prefer this over higher-volume bulk messaging services when simplicity and per-call billing are acceptable.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T13:29:17.850Z","isFirstParty":false}