{"uid":"cap_R372PaTeeNwYiKaf1BTss","slug":"fastapi-online-text-to-speech-tts-452275e8","name":"fastapi.online Text-to-Speech (TTS)","description":"Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding & crypto utilities, date/time calculators, geo/coordinate math, math & finance calculators, novelty tools, and business/social writing generators — 179 endpoints in all, across multiple specialized self-hosted models. Pay per call with crypto — no signup — or get an API key.","url":"https://api.fastapi.online/tts","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"text":{"type":"string","maxLength":2000,"minLength":1},"speed":{"type":"number","maximum":2,"minimum":0.5}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","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":"down","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_5WnB5Ps7OatCFJ3X42FRk","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Converts input text to audio using AI synthesis, returning base64-encoded audio with engine and format metadata","exampleAgentPrompt":"Can you convert this paragraph to speech at normal speed: 'Welcome to our platform. We're glad you're here and hope you enjoy the experience.'","exampleUseCases":[{"title":"Podcast script audio generation","prompt":"Take this script and turn it into audio I can use for my podcast intro: 'Hello and welcome to The Daily Tech Digest, your source for the latest in technology news.' Use a normal speaking speed."},{"title":"Accessibility audio for web content","prompt":"Convert this article summary into spoken audio so I can add it as an audio version for visually impaired users: 'Scientists have discovered a new species of deep-sea fish near the Mariana Trench.' Keep the speed at 1.0."},{"title":"Language learning pronunciation audio","prompt":"Generate a slow-speed speech audio of this French phrase so learners can hear the pronunciation clearly: 'Bonjour, comment allez-vous aujourd'hui?' Set the speed to 0.75."}],"resultDescription":"Returns a JSON object containing the audio encoded as a base64 string, along with the TTS engine used, the audio format (e.g. mp3, wav), and the sample rate of the output audio. The agent can decode the base64 string to obtain the raw audio file.","failureModes":["Missing required 'text' field returns a validation error","Very long text inputs may exceed model or timeout limits","Unsupported speed values may be clamped or cause errors","Payment failure (insufficient USDC) results in HTTP 402","Network timeout on slow inference"],"whenToPreferThis":"Choose this endpoint when you need a pay-per-call, no-signup TTS API that accepts crypto (USDC via x402 protocol). Ideal for agents that need occasional or bursty speech synthesis without committing to a subscription, or when operating in crypto-native payment flows. Best when base64 audio output is acceptable for downstream processing.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T10:28:25.982Z","isFirstParty":false}