{"uid":"cap_o2Tl4-2NZWP836A2cJTaq","slug":"fastapi-online-image-caption-3cb9eb3a","name":"fastapi.online Image Caption","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/image-caption","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"file":{"type":"string","format":"binary","description":"Image file (PNG/JPEG/WebP)"},"detail":{"type":"string","description":"short|detailed"}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.0015","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":"$0.0015/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.0015","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.0015","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_IKbyFT-5o3zg_cV5PPPDL","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.0015","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Generates a short or detailed natural-language caption for an uploaded image using a self-hosted vision model","exampleAgentPrompt":"Can you generate a detailed caption for this photo I'm uploading — describe everything you see in it?","exampleUseCases":[{"title":"Accessibility alt-text generation","prompt":"I need a short, descriptive alt-text caption for this product image I'm uploading so screen readers can describe it to visually impaired users."},{"title":"Social media post caption","prompt":"Write me a detailed caption describing everything in this photo so I can use it as a social media post — upload this JPEG and give me a rich description."},{"title":"Image content audit pipeline","prompt":"Describe what's in each of these images I'm sending — give me a short caption for each one so I can tag and organize them in my media library."}],"resultDescription":"A natural language string describing the visual contents of the uploaded image, either as a concise summary (short) or a rich, detailed description covering subjects, actions, setting, colors, and context (detailed).","failureModes":["Unsupported file format returns an error — only PNG, JPEG, and WebP are accepted","Very large or corrupted image files may fail to process","Ambiguous or abstract images may produce vague or low-confidence captions","Missing or empty file field results in a 400 bad request","Payment failure via x402 protocol will block the request before processing"],"whenToPreferThis":"Choose this endpoint when you need a low-cost, no-signup, pay-per-call image captioning solution with crypto payment support. Ideal for agents that process images on demand without committing to a subscription, or for workflows that require self-hosted inference without data leaving a controlled stack. Prefer this over large cloud vision APIs (e.g. Google Vision, AWS Rekognition) when cost per call and privacy matter more than SLA guarantees.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T01:05:08.521Z","isFirstParty":false}