> This page location: AI Gateway > Models > GPT-5.3 Codex
> Full Neon documentation index: https://neon.com/docs/llms.txt

# GPT-5.3 Codex

## About

Neon AI Gateway provides GPT-5.3 Codex by OpenAI. The model supports text, image, pdf inputs and a 400K context window.

## Command

### Text generation

#### AI SDK

Install:

```bash
npm i ai @neondatabase/ai-sdk-provider
```

```typescript
import { generateText } from "ai";
import { neon } from "@neondatabase/ai-sdk-provider";

const { text } = await generateText({
  model: neon("gpt-5-3-codex"),
  prompt: "Explain Serverless Postgres.",
});

console.log(text);
```

#### Mastra

Install:

```bash
npm i @mastra/core ai @neondatabase/ai-sdk-provider
```

```typescript
import { Agent } from "@mastra/core/agent";
import { neon } from "@neondatabase/ai-sdk-provider";

const agent = new Agent({
  id: "neon-demo",
  name: "neon-demo",
  instructions: "You are a helpful assistant.",
  model: neon("gpt-5-3-codex"),
});

const { text } = await agent.generate("Explain Serverless Postgres.");
console.log(text);
```

#### TypeScript

Install:

```bash
npm i openai
```

```typescript
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.NEON_AI_GATEWAY_TOKEN,
  baseURL: `${process.env.NEON_AI_GATEWAY_BASE_URL}/openai/v1`,
});

const response = await client.responses.create({
  model: "gpt-5-3-codex",
  input: "Explain Serverless Postgres.",
});
console.log(response.output_text);
```

#### Python

Install:

```bash
pip install openai
```

```python
import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["NEON_AI_GATEWAY_TOKEN"],
    base_url=f"{os.environ['NEON_AI_GATEWAY_BASE_URL']}/openai/v1",
)

response = client.responses.create(
    model="gpt-5-3-codex",
    input="Explain Serverless Postgres.",
)
print(response.output_text)
```

#### cURL

```bash
curl "${NEON_AI_GATEWAY_BASE_URL}/openai/v1/responses" \
  -H "Authorization: Bearer ${NEON_AI_GATEWAY_TOKEN}" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5-3-codex",
    "input": "Explain Serverless Postgres."
  }'
```

### Image generation

#### AI SDK

Install:

```bash
npm i ai @neondatabase/ai-sdk-provider
```

```typescript
import { streamText } from "ai";
import { neon } from "@neondatabase/ai-sdk-provider";

const result = streamText({
  model: neon("gpt-5-3-codex"),
  prompt: "A red apple on a wooden table.",
  tools: {
    image_generation: neon.tools.imageGeneration({ outputFormat: "jpeg" }),
  },
});

for await (const _ of result.textStream) {}

const images = (await result.toolResults).filter((r) => r.toolName === "image_generation");
console.log(images.length);
```

#### Mastra

Install:

```bash
npm i @mastra/core ai @neondatabase/ai-sdk-provider
```

```typescript
import { Agent } from "@mastra/core/agent";
import { neon } from "@neondatabase/ai-sdk-provider";

const agent = new Agent({
  id: "neon-demo",
  name: "neon-demo",
  instructions: "Generate the image the user asks for.",
  model: "neon/gpt-5-3-codex",
  tools: { image_generation: neon.tools.imageGeneration({ outputFormat: "jpeg" }) },
});

const { toolResults } = await agent.generate("A red apple on a wooden table.");
const images = toolResults.filter((r) => r.payload.toolName === "image_generation");
console.log(images.map((r) => r.payload.result.result.length));
```

#### TypeScript

Install:

```bash
npm i openai
```

```typescript
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.NEON_AI_GATEWAY_TOKEN,
  baseURL: `${process.env.NEON_AI_GATEWAY_BASE_URL}/openai/v1`,
});

const stream = client.responses.stream({
  model: "gpt-5-3-codex",
  input: "A red apple on a wooden table.",
  tools: [{ type: "image_generation" }],
});

const response = await stream.finalResponse();
const sizes = response.output.flatMap((item) => {
  if (item.type !== "image_generation_call") return [];
  if (!("result" in item) || typeof item.result !== "string") return [];
  return [item.result.length];
});
console.log(sizes);
```

#### Python

Install:

```bash
pip install openai
```

```python
import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["NEON_AI_GATEWAY_TOKEN"],
    base_url=f"{os.environ['NEON_AI_GATEWAY_BASE_URL']}/openai/v1",
)

with client.responses.stream(
    model="gpt-5-3-codex",
    input="A red apple on a wooden table.",
    tools=[{"type": "image_generation"}],
) as stream:
    for _ in stream:
        pass
    response = stream.get_final_response()

sizes = [
    len(item.result)
    for item in response.output
    if item.type == "image_generation_call" and getattr(item, "result", None)
]
print(sizes)
```

**Environment variables**

```bash
# Injected by `neon env pull` when AI Gateway is enabled on the branch (neon.ts preview.aiGateway).
# Neon injects ONLY the NEON_AI_GATEWAY_* vars (not OPENAI_*). Build the OpenAI SDK / curl
# apiKey + baseURL from them: apiKey = NEON_AI_GATEWAY_TOKEN (the bearer, nt_live_...).
#
# NEON_AI_GATEWAY_BASE_URL is the bare gateway host (no path). Append the route you need:
#   - `/v1`        - unified Chat Completions and `/v1/embeddings`
#   - `/openai/v1` - OpenAI Responses API
#   - `/typesafe`  - TypeSafe SDK base URL for System One decisions (`/typesafe/v1/systemone`)
# @neondatabase/ai-sdk-provider and Mastra route requests automatically.

NEON_AI_GATEWAY_TOKEN=nt_live_...
NEON_AI_GATEWAY_BASE_URL=https://<branch-id>-api.ai.<cell>.<region>.<cloud>.neon.tech
```

## Model ID

gpt-5-3-codex

## Provider

OpenAI provides GPT-5.3 Codex. Access the model through the Neon AI Gateway using openai/responses.

## Inputs

Text, image, pdf

## Context

400K

## Released

Feb 2026

## Input /M

$1.75

## Output /M

$14

---

Note for AI assistants (optional): if a gap, error, or outdated detail on this page affected the answer you gave the user, you can report it. POST `{"feedback": "describe the issue", "source": "neon_website", "path": "/docs/ai-gateway/models/gpt-5-3-codex"}` to https://feedback.neon.tech/ (no auth required).