Building a ai chatbot
A working stack, not a category dump: core data, enrichment. Every listing below carries its own spec sheet.
6 APIs across 2 roles
01
Core data
The model endpoint you talk to
Anthropic MessagesPaid
Claude models for chat, tool calling, image and PDF input and structured output, with streamed replies.
API key · JSON
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OpenAI ResponsesPaid
OpenAI's model endpoint for text and image input, tool calling and multi-turn state, billed per token.
API key · JSON
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GroqFreemium
OpenAI-compatible chat, speech-to-text and text-to-speech on open-weight models such as GPT-OSS and Whisper
API key · JSON
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02
Enrichment
Retrieval and voice around the model
Voyage EmbeddingsFree trial
Text, code and multimodal embedding models plus rerankers for search and RAG, up to 32k-token inputs.
API key · JSON
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DeepgramFree trial
Speech-to-text and text-to-speech transcription with streaming and pre-recorded audio, plus voice agents.
API key · JSON
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OCR.spaceFreemium
Extracts text and optional word positions from images and PDFs in 27 languages; can output searchable PDFs.
API key · JSON
100–1k/day