We route 90% of our traffic through the GPT-4.1 nano API — classification and extraction at a fraction of the cost. The 5% RouterBase discount is pure margin.
The GPT-4.1 nano API is OpenAI's fastest and cheapest 4.1 model — a 1M-token context window, vision (text + image input), function calling, and structured JSON outputs, tuned for low latency and high throughput. The GPT-4.1 nano API is OpenAI-compatible: point any existing SDK at RouterBase and set the model to gpt-4-1-nano. Input at $0.06 / 1M tokens, output at $0.24 / 1M tokens, cache reads at $0.015 / 1M tokens — 5% below the standard rate, all through one REST endpoint.
Input
GPT-4.1 nano
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GPT-4.1 nano API: Chat
Use the GPT-4.1 nano API to run OpenAI's fastest, cheapest 4.1 model with a 1M-token context window and vision.
The GPT-4.1 nano API is OpenAI's smallest and most cost-efficient 4.1 model — a 1M-token context window, vision (text + image input), function calling, and structured JSON outputs, tuned for low latency and high throughput. Routed through RouterBase, it is fully OpenAI-compatible: point any existing SDK at RouterBase's base URL, set the model to gpt-4-1-nano, and your first call goes through immediately.
Pricing is $0.06 / 1M input tokens, $0.24 / 1M output tokens, and $0.015 / 1M cached-input reads — 5% below the standard rate. One RouterBase key — no separate OpenAI credentials required.
Six reasons teams ship on the GPT-4.1 nano API
From 1M-token context to 5%-off pricing — what makes GPT-4.1 nano stand out.
1M-token context
Accepts up to 1 million tokens per request — long documents, multi-file code, or extended chat history fit in a single GPT-4.1 nano API call.
Vision input
The GPT-4.1 nano API accepts images alongside text. Pass an image URL or base64 in the same request to caption, extract, or reason over visual content.
Fastest, cheapest 4.1 tier
Built for high-volume workloads: the GPT-4.1 nano API is the lowest-cost model in the 4.1 family at $0.06 / 1M input tokens — ideal for classification, autocomplete, extraction, and routing at scale.
Function calling & JSON
Define tools and request a JSON schema; the GPT-4.1 nano API returns structured tool calls and strictly valid JSON for reliable agent and extraction pipelines.
OpenAI-compatible endpoint
The GPT-4.1 nano API speaks the OpenAI chat-completions wire format. Any Python, Node, Go, or Rust SDK that works with OpenAI works here — just update the base URL.
One key for 200+ models
The same RouterBase key that calls the GPT-4.1 nano API also routes to GPT-5, Claude Opus 4.8, Gemini 3.5 Flash, and 200+ other models — no per-provider credential management.
Quickstart
Get started with the GPT-4.1 nano API in 3 steps
From sign-up to your first response in under 5 minutes.
Create a RouterBase API key
Sign up and generate an API key — one key reaches the GPT-4.1 nano API and every other model in the catalog.
Send your first message
Point any OpenAI-compatible SDK at routerbase.com/v1 and set the model to gpt-4-1-nano. The response follows the standard chat-completions schema — streaming and vision supported.
Inspect usage
Every response includes a detailed token breakdown — input, output, and cache-read tokens — so cost and cache-hit rate are visible on every call.
Pay only for what you use
RouterBase passes through partner-tier pricing. Compared against the model's official published API rate.
What teams build with the GPT-4.1 nano API
Real production loads running on the GPT-4.1 nano API and the RouterBase model catalog.
Vision on the GPT-4.1 nano API replaced an OCR pipeline — one fast, cheap call captions and extracts, text and image together.
Structured JSON outputs from the GPT-4.1 nano API killed our flaky regex parsing. Strictly valid JSON every time, zero retries.
At our volume, GPT-4.1 nano is the only 4.1-class model that pencils out. RouterBase makes it 5% cheaper still.
Function calling on the GPT-4.1 nano API wires straight into my agent loop. Cheap enough that I stopped counting tokens.
RouterBase puts the GPT-4.1 nano API and 200+ other models behind one key. Our team stopped filing requests for new provider accounts.
We A/B the GPT-4.1 nano API against GPT-4.1 per request — same SDK, one model field. Most traffic stays on nano and the bill dropped 70%.
We migrated 42 services to the GPT-4.1 nano API over a weekend. The only PR comment was 'wait, that's all?'.
At $0.06 / 1M input minus 5%, the GPT-4.1 nano API made our high-volume features actually profitable. The ROI math was instant.
Frequently Asked Questions
Common questions about the GPT-4.1 nano API.
It is RouterBase's pass-through to OpenAI's GPT-4.1 nano — the fastest, cheapest 4.1-family chat endpoint with a 1M-token context, vision input, function calling, and structured outputs, served via an OpenAI-compatible REST interface.