Best LLM APIs & Model Routers
The best LLM API for coding agents in 2026 is the Claude API, because Opus 5.5 and Sonnet 5.5 lead on agentic coding and cheap cache reads keep long agent loops affordable.
The models behind your agents and AI features, with prices as checked.
Last checked · 5 ranked · editorial verdict · how we rank
The verdict
Claude API (Anthropic). Top coding/agent models (Opus 5.5 at $4/$20 per M tokens) with cheap cache reads for agent loops.
- #1
Claude API (Anthropic)
AnthropicWhy #1: Top coding/agent models (Opus 5.5 at $4/$20 per M tokens) with cheap cache reads for agent loops.
- Best for
- Coding agents and tool-heavy apps
- Pricing
- Per million tokens (input/output): Opus 5.5 $4/$20, Sonnet 5.5 $2/$10, Haiku 5.5 $0.50/$2.50, Fable 5.1 $10/$50. Prompt-cache reads discounted.
- #2
OpenAI API
OpenAIWhy #2: Widest range from GPT-6 Luna ($0.10/M input) to GPT-6 Astra; batch discounts.
- Best for
- General-purpose AI features at any budget
- Pricing
- Standard, per 1M tokens (short context, input/output): GPT-6 Astra $10/$50, GPT-6.1 Sol $2/$10, GPT-6 Luna $0.10/$0.50. Batch is ~50% off.
- #3
Gemini API
GoogleWhy #3: Free tier for prototyping and Gemini 4 Argon at introductory $2/$10 (through Nov 30, 2026).
- Best for
- Prototyping free; long-context work
- Pricing
- Free tier on eligible models. Gemini 4 Argon (paid tier): $2 input / $10 output per 1M tokens through Nov 30, 2026, rising to $4 / $20 from Dec 1, 2026.
- #4
OpenRouter
OpenRouterWhy #4: One key for 500+ models with routing and fallbacks; 5.5% fee.
- Best for
- Trying and switching models fast
- Pricing
- Free: 25+ free models, 50 requests/day. Standard pay-as-you-go with a 5.5% platform fee; Business 8%; Enterprise discounts.
- #5
Groq
GroqWhy #5: Very fast open-model inference; check current rates.
- Best for
- Latency-critical features
- Pricing
- Usage-based per-token pricing; check pricing (pricing page did not show rates when checked).check pricing
FAQ
What is the #1 pick in Best LLM APIs & Model Routers?
The best LLM API for coding agents in 2026 is the Claude API, because Opus 5.5 and Sonnet 5.5 lead on agentic coding and cheap cache reads keep long agent loops affordable.
Which tools made the Best LLM APIs & Model Routers list?
#1 Claude API (Anthropic) (best for: coding agents and tool-heavy apps); #2 OpenAI API (best for: general-purpose ai features at any budget); #3 Gemini API (best for: prototyping free; long-context work); #4 OpenRouter (best for: trying and switching models fast); #5 Groq (best for: latency-critical features).
What's the cheapest way to start with Claude API (Anthropic)?
Per million tokens (input/output): Opus 5.5 $4/$20, Sonnet 5.5 $2/$10, Haiku 5.5 $0.50/$2.50, Fable 5.1 $10/$50. Prompt-cache reads discounted. (Checked 2026-10-22.)
Should I use a router like OpenRouter?
Yes while experimenting; consider going direct to a provider once you settle on a model to avoid the fee.