Developer APIs & SDKs

Google's browser-based workspace for testing Gemini prompts and building AI features. Free usage is available before teams need paid scale.

A very fast inference platform with free playground access and developer-friendly APIs. Great for low-latency demos and prototype apps.

Model hosting and inference for open-source AI, with chat access and developer APIs. Free credits make it useful for early-stage testing.

A single API that routes requests across many models and providers. Some models are free, which makes it handy for testing without vendor lock-in.

An open-source framework for search, retrieval, RAG, and agent pipelines. It's a workhorse for developers building serious AI back ends.

A high-performance inference engine for serving large language models efficiently. Excellent for developers who need speed, batching, and less GPU heartbreak.

Hugging Face's core library for working with transformer models across NLP, vision, and audio. Basically one of the default toolboxes for AI developers now.

A framework for connecting LLMs to documents, databases, and APIs. Good for building retrieval and agent systems without reinventing half the stack.

A widely used framework and ecosystem for building LLM apps, chains, agents, and evaluation workflows. Useful when projects get more complex than a single prompt box.

A framework for orchestrating multiple AI agents around shared goals and tasks. Good for developers building agent teams instead of one lonely chatbot.

Microsoft's framework for building multi-agent applications and workflows. A solid pick for experiments where agents need to collaborate, hand off, and reason together.

A dead-simple Python tool for turning AI demos into shareable web apps. Perfect for prototypes, internal tools, and model showcases.

The reference API for GPT, embeddings, vision, and audio models. Free trial credits help new devs get to a working prototype quickly.

Direct API access to Claude models for chat, analysis, and long-context tasks. Free trial credits make early integration painless.

Google's API for Gemini models, including multimodal and long-context features. Free quota in AI Studio is generous for prototypes.

Hosted access to Mistral's open and commercial models with a clean API. Free credits and competitive pricing for serious experiments.

An enterprise-friendly NLP API with strong embeddings, rerank, and generation models. A free trial tier helps teams evaluate before they commit.

Run thousands of open-source AI models via a single API with pay-per-second billing and free trial credits. Handy for image, audio, and niche models.

Fast inference API for image, video, and audio models with a developer-first feel. Free credits get you to working media pipelines quickly.

High-performance inference for open-source models with a free playground and trial credits. Useful for low-latency LLM and embedding workloads.

Pay-as-you-go inference for popular open models with simple APIs and free credits to start. A budget-friendly option for production workloads.

Speech-to-text, speaker diarisation, and audio intelligence APIs with free monthly credits. A solid pick for transcription and call analytics.

Streaming and batch speech APIs with strong accuracy and a free starting credit. Great for voice agents and live captioning.

Realistic text-to-speech and voice cloning APIs with a free tier for short-form audio. Widely used for narration, demos, and voice apps.

APIs for Stable Diffusion and related image, video, and audio models. Free trial credits help you put a generative back end together quickly.

Managed vector database for retrieval and RAG with a usable free Starter tier. Common building block for AI search and agents.

Hosted vector database from the open-source Weaviate project, with a free sandbox for getting started. Good fit for hybrid search and RAG.

Managed vector search built on the open-source Qdrant engine, with a free cluster tier. Fast, friendly, and runs anywhere if you outgrow the cloud.

An open-source embedding database for AI apps that runs locally or in the cloud. Easy to drop into LangChain or LlamaIndex stacks.

Serverless GPU and CPU compute for Python with a generous free monthly credit. Great for running AI jobs and background workers without ops drama.

GPU cloud with serverless endpoints and pod rentals, plus free trial credits. Useful for training, inference, and stable-diffusion-style workloads.

A developer-first email API with React Email components and a free monthly send allowance. Pleasant alternative to legacy mail providers.

Twilio's transactional and marketing email platform with a free tier for low-volume senders. A long-standing default for app-generated email.

Reliable transactional email with a free developer plan for small projects. Known for fast delivery and clean dashboards.

SMS, voice, WhatsApp, and verification APIs with free trial credits to build and test. The default toolkit for adding comms to an app.

Payments, subscriptions, and billing APIs that are free to integrate; you only pay per successful charge. Test mode is unlimited and properly featured.

Hosted search APIs with a generous free tier of records and operations. Great when you want fast typo-tolerant search without running your own cluster.

An open-source search engine with a friendly API and a free cloud sandbox. Easy to self-host and surprisingly capable out of the box.

Open-source typo-tolerant search with a hosted cloud and a free trial tier. A solid Algolia alternative for builders watching the budget.

Maps, geocoding, navigation, and tiles APIs with a free monthly allowance for most services. The default for custom-styled web and mobile maps.

Community-built world map data, free to use under open licence. The bedrock under countless apps that don't want to pay rent on the planet.

Drop-in authentication and user management with a friendly free tier. Saves teams weeks compared to rolling auth themselves.

Veteran identity platform with social login, SSO, and a free tier for small apps. Still a sensible default when auth needs to be airtight.

Open-source product analytics, feature flags, and session replay with a generous free cloud tier. Great for builders who want insights without spyware vibes.

Error monitoring and performance tracing for almost every stack, with a free developer tier. Indispensable when production breaks at 2am.

Privacy-friendly, open-source web analytics with a clean dashboard. Self-host for free or use the paid cloud if you'd rather not.

Open-source, self-hostable web analytics with a simple UI and respect for visitors. A solid free alternative to Google Analytics.

Voice AI APIs for building phone agents and voice assistants, with free trial minutes. Useful for builders chasing the voice-first wave.