Get started with GPT‑4.1 mini's API in no time

Introduction to GPT‑4.1 mini

GPT‑4.1 mini is the smaller, cheaper sibling in the GPT‑4.1 family. It still supports a 1,000,000‑token context window, keeps the multimodal chops (text + images), and answers around 2× faster than the flagship model — all while cutting costs by 80 % (see pricing below). Benchmarks show it outruns GPT‑4o in many tasks and lands just a few points shy of full GPT‑4.1 on MMLU and coding tests.

New to LLMs? Read my quick explainer on how GPT‑style models work, then come back ready to build.

Create an account to get your GPT‑4.1 mini API key

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Go to Billing overview and add credit so your new keys work immediately.

Adding credit so the key works right away

Generate an API key. Copy it to a password manager as you will never see the full string again.

API key generation on OpenAI

Key in hand? Time to call the model.

How to make your first request to GPT‑4.1 mini

macOS and Linux:

curl -X POST \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  https://api.openai.com/v1/chat/completions -d '{
    "model": "gpt-4.1-mini",
    "messages": [
      { "role": "system", "content": "You are an assistant." },
      { "role": "user", "content": "Hello!" }
    ]
  }'

Windows (one‑liner):

curl -X POST -H "Content-Type: application/json" -H "Authorization: Bearer %OPENAI_API_KEY%" https://api.openai.com/v1/chat/completions -d "{ \"model\": \"gpt-4.1-mini\", \"messages\": [{\"role\":\"user\",\"content\":\"Hello!\"}] }"

Pro tip: The alias gpt‑4.1‑mini always points to the newest mini weights so you get silent upgrades.

Token budget: one call can ingest up to 1,000,000 tokens and spit out up to 32,768 tokens in the reply.

Example response from GPT‑4.1 mini

How to enable JSON mode with GPT‑4.1 mini

JSON mode works exactly as on the full version. Add the response_format object and the model will only output valid JSON that matches your schema.

curl -X POST \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  https://api.openai.com/v1/chat/completions -d '{
    "model": "gpt-4.1-mini",
    "messages": [
      { "role": "system", "content": "Serve answers as tight JSON." },
      { "role": "user", "content": "Solve 8x + 31 = 2." }
    ],
    "response_format": {
      "type": "json_schema",
      "json_schema": {
        "strict": true,
        "schema": {
          "type": "object",
          "properties": {
            "steps": { "type": "array", "items": { "type": "string" } },
            "final_answer": { "type": "string" }
          },
          "required": ["steps", "final_answer"],
          "additionalProperties": false
        }
      }
    }
  }'

Stay mindful of your token budget; the schema itself counts.

GPT‑4.1 mini pricing

Model	Input (per 1 M)	Output (per 1 M)
gpt‑4.1 mini (1 M context)	$0.40	$1.60
gpt‑4.1 (1 M context)	$2.00	$8.00
gpt‑4.1 nano (1 M context)	$0.10	$0.40

Ten project ideas where GPT‑4.1 mini shines

Real‑time chat moderation: Millions of messages in context, near‑instant answers, low cost.
Docstring generators on save: Run the model on every file change without blowing budget.
Edge‑deployable analytics: Summarise log batches locally then sync compressed insights.
Smart IoT dashboards: Digest sensor dumps and annotate anomalies on the fly.
Lightweight knowledge bots: Keep your startup’s wiki inline without touching the flagship model.
Bulk PDF reformatting: Convert long regulatory filings into clean HTML at scale.
Quick code review assistants: Get inline suggestions before pushing to CI.
Adaptive flashcard makers: Feed class notes and generate study decks in seconds.
Marketing A/B copy labs: Spin dozens of variants while staying within ad budget.
Continuous sentiment guards: Monitor brand chatter with minute‑level cadence without breaking the bank.