How do I reduce my Cursor API bill?

Cursor Pro's $20/mo covers 500 fast requests — past that you pay OpenAI / Anthropic per-call rates directly, which is why heavy users end up at $50-$200/mo. The fix is to point Cursor's Custom API at CodeRouter and set model to 'auto'. CodeRouter detects what phase of coding the request is (planning, implementation, debugging, test generation, docs) and routes to the cheapest capable model per phase — Opus only for planning, DeepSeek V4 Pro for implementation and test generation, Haiku for docstrings. Same Cursor IDE, same keyboard shortcuts, 70-90% lower monthly bill. Setup takes 2 minutes — just change base_url to https://www.coderouter.io/api/v1 and paste your cr_ API key.

What is the cheapest API for Claude Code / Aider / Copilot?

There isn't a single 'cheapest API' — the cheapest model depends on what the coding agent is doing. For planning and architecture, you still want Claude Opus 4.8 or Sonnet 4.6. For implementation, DeepSeek V4 Pro ($0.44/$0.87 per 1M) and Kimi K2.6 are 15-40x cheaper than Opus with near-equivalent code quality. For test generation, DeepSeek V4 Pro or GLM-5.2 is 15-50x cheaper. For docstrings and simple formatting, Haiku 4.5 ($1/$5) or Gemini 2.5 Flash ($0.30/M output) is 15-250x cheaper. CodeRouter is the gateway that picks per request automatically — aim a single base_url at https://www.coderouter.io/api/v1 from Claude Code, Aider, Copilot (via LiteLLM), Cursor, Windsurf, or any OpenAI-compatible agent.

Does DeepSeek V4 Pro work as well as Claude Sonnet for coding?

For implementation and test generation phases — yes, DeepSeek V4 Pro matches Claude Sonnet 4.6 on HumanEval, MBPP, and LiveCodeBench within 1-3 points. For multi-file refactoring and architecture planning, Sonnet still has an edge on long-context reasoning. DeepSeek V4 Pro costs $0.44 input / $0.87 output per 1M tokens after the July 2026 price cut, vs Sonnet's $3/$15 — roughly 7-17x cheaper. The right answer for most coding agents is not 'pick one forever' but 'use DeepSeek V4 Pro for the implement/test phases and Sonnet or Kimi K3 for the plan/refactor phases.' That's phase-aware routing in practice — CodeRouter decides per request in ~10ms.

What is phase-aware LLM routing?

Phase-aware LLM routing classifies each coding-agent request by what phase of software work it represents — planning, implementation, debugging, testing, refactoring, or documentation — and routes it to the cheapest model that can handle that specific phase. A 'write unit tests for this function' request goes to DeepSeek V4 Pro ($0.87/M output). A 'refactor this multi-file feature and plan the migration' request goes to Claude Opus 4.8 ($25/M output). This is different from picking one model for everything, and different from OpenRouter-style model-selection (which still requires you to choose manually). CodeRouter's classifier runs in ~10ms on the server, so the agent never notices the extra hop.

CodeRouter vs OpenRouter — which saves more money on coding?

OpenRouter is a model marketplace — it gives you access to 300+ models behind one API key, but you still pick which model to send each request to. Most Cursor / Aider / Claude Code users default to the premium model (Opus, GPT-5) for everything and end up paying full price. CodeRouter is a phase-aware router — set model to 'auto' and we pick the cheapest capable model per request based on the coding phase. CodeRouter also adds things OpenRouter doesn't: coding-specific capability scores per model (implementation, debug, test, refactor), per-end-user attribution for SaaS agent builders, and built-in quota + top-up billing. For pure coding workloads, typical CodeRouter savings are 70-90% vs picking one model on OpenRouter.

Will CodeRouter break my Cursor / Aider / Claude Code agent?

No. CodeRouter exposes a standard OpenAI-compatible chat completions endpoint (POST /api/v1/chat/completions) with the same request and response format your agent already uses — including streaming, tool use, and function calling. We implement the same JSON schema and stream format, so Cursor, Aider, Claude Code, Cline, Continue.dev, Windsurf, OpenClaw, and any LiteLLM-wrapped client work unmodified. If a routed model fails, the fallback chain tries up to 2 alternates automatically (on 429, 500-504, timeouts, missing keys). You can also pin an explicit model instead of 'auto' any time.

How do I set up CodeRouter with Cursor in 2 minutes?

1) Sign up free at https://www.coderouter.io/login and copy your API key (starts with cr_). 2) In Cursor, open Settings -> Models -> OpenAI API Key, and under 'Override OpenAI Base URL' paste https://www.coderouter.io/api/v1. Paste your cr_ key in the API Key field. 3) Add 'auto' to the Custom Models list and select it as your active model. That's it — phase-aware routing is live. Aider users set OPENAI_API_BASE and OPENAI_API_KEY env vars to the same values. Claude Code users set ANTHROPIC_BASE_URL to https://www.coderouter.io/api/v1 and ANTHROPIC_API_KEY to the cr_ key. Full guide at https://www.coderouter.io/setup.

Changelog

What changed in CodeRouter, newest first. This page covers changes that affect requests going through the router — models added or retired, routing rules, provider failover behaviour, billing and API endpoints.

Current model lineup and per-phase scores: models · Setup per agent: integration guide · How routing decides: about

September 2026

APIMCP server at /api/mcp — coding agents that speak Model Context Protocol can query the verified LLM error database directly with lookup_llm_error and list_llm_errors, without leaving the editor.
DocsLLM API error reference expanded to cover the OpenAI quota, context-length, model_not_found and invalid_api_key families; the Anthropic credit-balance, 529 overloaded and prompt-too-long errors; Gemini RESOURCE_EXHAUSTED; and connection-refused against local Ollama / LM Studio endpoints.
DocsNew resolution pages for proxy-layer failures that official docs do not cover: Unknown parameter 'output_config', tool_result / tool_use id mismatches, and anthropic-beta headers rejected by non-Anthropic upstreams.
BillingThe Free (BYOK) tier was discontinued and removed from the pricing page and structured data. Current plans are on the pricing page.

August 2026

RoutingKimi K3 weight raised — a 20% boost on high-complexity requests plus position promotions in the implementation and refactor pools, following internal quality testing.
DocsThe LLM API Error Reference was published: real errors indexed by their exact error string, each with cause and fix.
APIllms.txt gained a 'when to use' section and a draft OpenAPI specification was added for the routing API.

July 2026

ModelsKimi K3 integrated through a direct Moonshot endpoint rather than an aggregator, reducing a hop on every K3 request.
ModelsClaude Opus 4.8 added to the planning and architecture pools.
RoutingRouting transparency added to the dashboard — each request now shows which model was selected and which phase was detected.
BillingPricing guards added to prevent plan changes from applying stale prices, alongside corrections to several published per-model prices.

June 2026

ModelsGLM-5.1 upgraded to GLM-5.2 with a verified 1M-token context window.
RoutingGLM-5.2 added to the Anthropic-shape overlay's long-context slot, so long-context requests arriving in Anthropic format no longer fall through to a premium model by default.
ModelsRequests pinned to the retired gemini-3-pro identifier are now migrated automatically instead of failing with a 404.

May 2026

ModelsDeepSeek V4-Pro's permanent 75% price cut applied across the routing tables, which changed cost ordering for implementation and test-generation requests.
RoutingRequests that enable thinking mode are now restricted to models that actually support it, instead of being silently downgraded.
RoutingVision-aware phase preference — requests carrying images are routed only to models that can read them.
RoutingPhase detector v2: tool-call inference, multi-turn defaults and Chinese-language prompt patterns, plus a conservative fallback for requests that cannot be classified.
ProvidersProvider-level cooldown added so that one upstream outage degrades gracefully instead of cascading through a session. HTTP 402 Insufficient Balance is now treated as an auth-tier cooldown rather than a retryable error.
API/api/v1/responses endpoint added for OpenAI Codex compatibility.
BillingDaily auto-topup cap and a card-on-file gate added, so a runaway agent loop cannot drain a balance unbounded.
RoutingSmart routing is now enforced on Studio and Team plans — explicit model pins are rewritten to auto, because per-request routing is the product.

April 2026

RoutingCodeRouter launched as a phase-aware router for coding agents, with per-phase capability scoring rather than a single general-purpose model score.