gpt-4-1-nano
GPT-4.1 nano is the fastest and cheapest model in the GPT-4.1 series, built for low-latency tasks while keeping a 1M-token context window.
Pricing: Input 20 credits / 1M tokens (≈ $0.10), Output 80 credits / 1M tokens (≈ $0.40).
Prices updated
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GPT-4.1 Nano API on ModelFold
GPT-4.1 nano is the fastest and cheapest model in the GPT-4.1 series, built for low-latency tasks while keeping a 1M-token context window. Try GPT-4.1 Nano in the ModelFold Playground, then call it from your own code through an OpenAI-compatible chat completions API.
What Is the GPT-4.1 Nano API
GPT-4.1 Nano at a glance
GPT-4.1 Nano is a chat model from OpenAI. It accepts text, images and files (such as PDF) as input and returns text, with a context window of up to 1M tokens.
Use it without hosting anything
On ModelFold you call GPT-4.1 Nano with a single API key — no model weights to download and no inference servers to run. The same key also works for the other chat, image, video and audio models on ModelFold.
Core Capabilities of GPT-4.1 Nano
Up to 1M tokens of context
Keep long conversations, large documents and sizeable code in a single request, so the model can reason over the full material instead of fragments.
Understands images and files (such as PDF)
Besides text, GPT-4.1 Nano accepts images and files (such as PDF) as input, so a single request can combine instructions with visual or other media.
Function calling
GPT-4.1 Nano supports tool (function) calling: describe your functions in the request and the model returns structured calls your code can run — the basis for agents and integrations.
Structured outputs
Ask for JSON that follows a schema (response_format), which makes extraction, classification and system integrations more reliable.
How to Use GPT-4.1 Nano on ModelFold
- 1
Step 1: Try it in the Playground
Open the Playground at the top of this page, type a prompt and see how GPT-4.1 Nano responds before writing any code.
- 2
Step 2: Create an API key
Sign in to ModelFold and create an API key in the console. Keep it secret and send it as a Bearer token.
- 3
Step 3: Send a request
Call POST https://modelfold.ai/v1/chat/completions with "model": "gpt-4-1-nano" and your messages. Existing OpenAI-compatible SDKs work by changing the base URL and key.
- ✓
Step 4: Ship and monitor
Integrate the response into your product and check token usage and spend for every call in the console logs.
What You Can Build with GPT-4.1 Nano
Low-latency experiences
Power chat interfaces, autocomplete and interactive tools where users expect fast responses.
High-volume pipelines
Run classification, extraction, rewriting and batch jobs at scale where cost per request matters.
Long-document workflows
Feed in long reports, contracts, manuals or codebases and ask for summaries, comparisons and answers grounded in the material.
Tool-calling backends
Route requests, call functions and chain API calls as the worker model inside larger agent systems.
Frequently Asked Questions
What is GPT-4.1 Nano?⌄
GPT-4.1 nano is the fastest and cheapest model in the GPT-4.1 series, built for low-latency tasks while keeping a 1M-token context window.
Which inputs does GPT-4.1 Nano support?⌄
GPT-4.1 Nano accepts text, images and files (such as PDF) and returns text. Through ModelFold you can send text and images (OpenAI-style image_url content); in the Playground you can also attach documents, which are converted to text.
How long is the context window of GPT-4.1 Nano?⌄
Up to 1M tokens, shared between your input and the model’s output.
Does GPT-4.1 Nano support function calling?⌄
Yes. GPT-4.1 Nano supports tools / function calling through the standard tools parameter of the chat completions API.
How is GPT-4.1 Nano billed on ModelFold?⌄
Pay as you go by tokens: input and output tokens are charged at the per-million-token prices shown on this page. There is no monthly fee, and failed requests are not charged.
How do I call GPT-4.1 Nano through the API?⌄
Send a POST request to https://modelfold.ai/v1/chat/completions with "model": "gpt-4-1-nano", using your ModelFold API key as the Bearer token.
| Input | 20 credits 1M tokens≈ $0.10 |
| Output | 80 credits 1M tokens≈ $0.40 |
Billed per token: input and output are priced separately, and thinking tokens count as output. The Playground charges exactly the same way.
Read API docs →AI Agents · Claude Code / Cursor / Trae →curl https://modelfold.ai/v1/chat/completions \
-H "Authorization: Bearer $MODELFOLD_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"gpt-4-1-nano","messages":[{"role":"user","content":"Hello"}]}'