API Building Blocks
Discover the APIs behind chat, UI, voice, video, data, automation, and agents. Compare capabilities and choose the right building blocks for headless and agentic software.
10 listings
Algolia Search API
- Summary
- A hosted search and discovery API for indexing records, running keyword and AI-assisted search, configuring ranking, filtering results, and adding recommendations and personalization.
- Category
- UI & Experiences
- Pricing model
- Freemium
- Authentication
- API key
- Free tier
- Yes
- Open source
- No
Clerk Backend API
- Summary
- An identity and user management API for users, sessions, organizations, invitations, tokens, machine authentication, API keys, and application authentication workflows.
- Category
- Identity & Security
- Pricing model
- Freemium
- Authentication
- Bearer token
- Free tier
- Yes
- Open source
- No
ElevenLabs API
- Summary
- A voice and audio API for text to speech, speech to text, conversational voice agents, dubbing, sound effects, voice transformation, and audio processing.
- Category
- Voice & Audio
- Pricing model
- Freemium
- Authentication
- API key
- Free tier
- Yes
- Open source
- No
HeyGen API
- Summary
- A video generation API for creating avatar videos, translating and dubbing video, generating speech, producing videos from templates, and working with avatar, voice, and template libraries.
- Category
- Video & Avatars
- Pricing model
- Usage-based
- Authentication
- API key
- Free tier
- No
- Open source
- No
Inngest API
- Summary
- A durable execution and workflow API for event-driven functions, background jobs, queues, retries, concurrency, throttling, scheduling, and workflow observability.
- Category
- Automation & Orchestration
- Pricing model
- Freemium
- Authentication
- API key
- Free tier
- Yes
- Open source
- Yes
OpenAI API
- Summary
- A model API for building text, reasoning, multimodal, realtime, image, audio, and agentic applications through hosted models and tools.
- Category
- Models & Agents
- Pricing model
- Usage-based
- Authentication
- API key
- Free tier
- No
- Open source
- No
Pinecone API
- Summary
- A managed vector database and inference API for storing and searching records, generating embeddings, reranking results, and building retrieval and knowledge applications.
- Category
- Data & Knowledge
- Pricing model
- Freemium
- Authentication
- API key
- Free tier
- Yes
- Open source
- No
Resend API
- Summary
- An email API for sending and receiving transactional email, managing domains, contacts, broadcasts, templates, webhooks, and delivery events.
- Category
- Chat & Messaging
- Pricing model
- Freemium
- Authentication
- API key
- Free tier
- Yes
- Open source
- No
Stripe API
- Summary
- A payments and financial infrastructure API for accepting payments, managing subscriptions, sending payouts, running platforms and marketplaces, and automating revenue workflows.
- Category
- Payments & Commerce
- Pricing model
- Usage-based
- Authentication
- API key
- Free tier
- No
- Open source
- No
Vercel REST API
- Summary
- A platform API for managing deployments, projects, domains, environment variables, logs, caches, integrations, teams, and other application infrastructure.
- Category
- Infrastructure & Observability
- Pricing model
- Freemium
- Authentication
- Bearer token
- Free tier
- Yes
- Open source
- No