LLM API guides: build, compare and operate with confidence
Start with the API contract, choose a gateway or router, model the real cost and connect the coding agents your team uses. Every guide is grouped by the decision you are trying to make.

Which guide should you read first?
Connect an API client
Create a key, set the base URL and test a direct request before adding routing or orchestration.
Platform choiceChoose a gateway
Compare hosted, self-hosted, marketplace and governance-heavy operating models.
Budget decisionPrice the workload
Model tokens, retries and team size before comparing model rates or changing providers.
Protocol and API access
Start with the request contract, then add the right endpoint, limits and fallback path.
OpenAI-compatible quickstart
Create a key, call /v1/chat/completions and review endpoints, billing and error codes.
What is an OpenAI-compatible API?
Understand compatibility, migration and the protocol paths your SDK actually uses.
LLM API rate limits and 429 recovery
Diagnose RPM, TPM, concurrency and Retry-After, then build a bounded retry budget.
LLM API fallback and failover
Build a safe retry and model-fallback chain without hiding quality or side-effect failures.
LLM API timeout diagnosis
Separate connect, first-token, idle and total deadlines, then recover without duplicate work.
Free LLM APIs: limits and real cost
Compare public free tiers, expiry, data terms and when paid inference is cheaper.
What is an LLM API aggregator?
Learn how one endpoint, catalogue, meter and bill fit together.
OpenRouter alternative checklist
Evaluate catalogue, pricing, billing, regions and migration before switching.
Gateway and router selection
Separate access, routing and governance before comparing product names.
How to choose an AI API gateway
Compare hosted, self-hosted, marketplace and governance-heavy operating models.
What is an LLM router?
Decide when model routing is worth its policy, evaluation and failure overhead.
LLM gateway alternatives
Shortlist six managed, marketplace and self-hosted options by control model.
AI API gateway pricing
Work through model, request, retry, plan and operational costs.
Enterprise gateway procurement
Prepare the security, contract, access, audit and support checklist.
AI API gateway security
Review prompts, keys, upstream providers, retention and model substitution.
LiteLLM vs OpenRouter
Compare self-hosted control with a hosted model marketplace.
OpenLux vs OpenRouter
Compare catalogue breadth, billing and managed operations.
OpenLux vs Requesty
Compare advanced routing controls with a focused hosted catalogue.
Cost and optimization
Measure accepted-task cost instead of ranking providers by token price alone.
LLM API cost calculator
Turn sessions, tokens, retries and team size into a monthly API estimate.
AI cost optimization
Reduce context, retries and model tier without shifting cost into review.
How to find the cheapest LLM API
Compare delivered cost across models, modalities, plans and retries.
LLM prompt caching
Compare Claude, GPT and Gemini cache behavior and billing fields.
Coding agent cost comparison
Compare Claude Code, Codex, Cursor, Aider and Cline cost structures.
Claude Code cost
Model repository context, sessions and retries for a team budget.
Codex CLI cost
Estimate terminal-agent tasks, context and monthly team spend.
Cursor API cost
Separate the editor plan from routed custom-endpoint usage.
Coding agents and operations
Connect the clients your team already uses and add bounded review automation.
Build an AI code reviewer
Review pull-request diffs with Python, CI, evidence and human approval.
LLM API observability
Define safe request logs, useful metrics, traces and actionable alerts.
Developer and client integrations
Choose an IDE, terminal agent, chat client or framework for your workflow.
Codex CLI + OpenLux
Configure a custom provider in ~/.codex/config.toml.
Claude Code + OpenLux
Use a local compatible bridge for an Anthropic-style client.
Cursor + OpenLux
Connect Cursor to an OpenAI-compatible custom endpoint.
OpenCode + OpenLux
Register OpenLux through opencode.json and the OpenAI-compatible package.
Cline + OpenLux
Run a VS Code coding agent on the shared model endpoint.
Tool-calling models
Compare models that can support structured agent tool loops.
Use one endpoint for the guides you just read
OpenAI-compatible access, published model prices and request-level usage in USD. Start with trial credit, then scale the workload you measured.