OpenRouter

Routes API requests to multiple LLM providers (OpenAI, Anthropic, Google, Meta, Mistral, etc.) through a single standardized endpoint, abstracting provider-specific API schemas and authentication. Implements a request normalization layer that translates unified OpenRouter API calls into provider-native formats, handling differences in parameter naming, token counting, and response structures across 100+ models.

Enables function calling across providers with different native function-calling implementations (OpenAI's tool_choice, Anthropic's tool_use, etc.) by accepting a unified JSON schema and translating it to each provider's format. Handles response parsing to extract function calls regardless of provider-specific response structure, normalizing tool_calls into a consistent format.

Exposes real-time pricing data (input/output token costs) for all available models, enabling developers to programmatically select models based on cost-performance tradeoffs. Provides model metadata including context window size, training data cutoff, and capabilities, allowing cost-aware routing logic without manual price lookups.

Supports Server-Sent Events (SSE) streaming for real-time token generation across all providers, normalizing streaming response formats (OpenAI's delta objects, Anthropic's content_block_delta, etc.) into a unified stream format. Handles stream interruption, error propagation, and graceful fallback to non-streaming responses.

Automatically logs all API requests and responses with metadata including provider, model, tokens used, latency, and cost. Provides dashboard and API access to request history, enabling usage analytics, cost tracking, and performance monitoring across all providers without application-level instrumentation.

Provides accurate token counting for each model using model-specific tokenizers (not generic approximations), accounting for differences in how providers count tokens (e.g., OpenAI vs. Anthropic token boundaries). Exposes context window limits and handles context overflow warnings before requests are sent.

Implements automatic failover to alternative providers/models when a request fails, with configurable retry policies (exponential backoff, max retries, timeout handling). Transparently switches providers based on availability, error type, and user-defined fallback chains without requiring application-level retry logic.

Exposes structured metadata about model capabilities (vision support, function calling, long context, etc.) enabling programmatic filtering and discovery. Allows querying models by capability (e.g., 'find all models with vision support under $0.01 per 1K tokens') without manual research or hardcoded model lists.

Manages rate limits and quotas across multiple providers, tracking usage per model, provider, and time window. Implements client-side rate limiting to prevent hitting provider limits, with configurable quota policies and transparent quota enforcement without application-level tracking.

Caches identical prompts and their responses to avoid redundant API calls, with configurable cache TTL and invalidation policies. Detects duplicate requests and returns cached responses transparently, reducing latency and costs for repeated queries without application-level caching logic.