Gemini API

The Gemini endpoint exposes the Google Gemini API through Neon AI Gateway. Use it when you're already working with the google genai SDK and want to keep your existing code. For most use cases, the cha...

The Gemini endpoint exposes the Google Gemini API through Neon AI Gateway. Use it when you're already working with the google-genai SDK and want to keep your existing code. For most use cases, the chat completions endpoint is simpler to set up and works with Gemini models via the OpenAI SDK.

Supported actions: :generateContent and :streamGenerateContent

Endpoint pattern: https://<branch-host>/gemini/v1beta/models/<model>:<action>

This endpoint is also reachable at the longer /ai-gateway/gemini/v1beta/models/<model>:<action> path. Both behave identically and neither is deprecated. See Shorter paths for the full list of aliases.

Setup

Set these environment variables. See Get started for how to obtain them.

Bash

NEON_AI_GATEWAY_TOKEN=nt_live_...
NEON_AI_GATEWAY_BASE_URL=https://br-winter-pond-aptw82ef-api.ai.c-2.us-east-2.aws.neon.tech

Supported models

This endpoint accepts Google models only:

Model ID	Notes
`gemini-3-6-flash`
`gemini-3-5-flash`
`gemini-3-5-flash-lite`
`gemini-3-1-pro`
`gemini-3-1-flash-lite`
`gemini-3-flash`

Sending a non-Google model ID returns 400 model "<model-id>" is not available on the gemini_generate_content endpoint, naming whichever model you sent. Use the chat completions endpoint if you want to call Gemini models alongside other providers from the same code.

Basic request

TypeScript (google-genai)

import { GoogleGenAI } from '@google/genai';

const client = new GoogleGenAI({
  apiKey: 'placeholder',
  httpOptions: {
    baseUrl: `${process.env.NEON_AI_GATEWAY_BASE_URL}/gemini`,
    headers: {
      Authorization: `Bearer ${process.env.NEON_AI_GATEWAY_TOKEN}`,
    },
  },
});

const response = await client.models.generateContent({
  model: 'gemini-3-flash',
  contents: [{ role: 'user', parts: [{ text: 'What is Neon?' }] }],
});

console.log(response.text);

Python (google-genai)

from google import genai
from google.genai import types
import os

client = genai.Client(
    api_key='placeholder',
    http_options=types.HttpOptions(
        base_url=f"{os.environ['NEON_AI_GATEWAY_BASE_URL']}/gemini",
        headers={'Authorization': f"Bearer {os.environ['NEON_AI_GATEWAY_TOKEN']}"},
    ),
)

response = client.models.generate_content(
    model='gemini-3-flash',
    contents='What is Neon?',
)

print(response.text)

cURL

curl -X POST \
  "$NEON_AI_GATEWAY_BASE_URL/gemini/v1beta/models/gemini-3-flash:generateContent" \
  -H "Authorization: Bearer $NEON_AI_GATEWAY_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [{"role": "user", "parts": [{"text": "What is Neon?"}]}]
  }'

Streaming

TypeScript (google-genai)

const stream = await client.models.generateContentStream({
  model: 'gemini-3-flash',
  contents: [{ role: 'user', parts: [{ text: 'Explain database branching.' }] }],
});

for await (const chunk of stream) {
  process.stdout.write(chunk.text ?? '');
}

Python (google-genai)

for chunk in client.models.generate_content_stream(
    model='gemini-3-flash',
    contents='Explain database branching.',
):
    print(chunk.text, end='', flush=True)

URL structure

The gateway uses the model ID and action directly in the URL path. The google-genai SDK constructs this automatically from the base URL and model parameter:

base_url: https://<branch-host>/gemini
model:    gemini-3-flash
action:   generateContent or streamGenerateContent

→ https://<branch-host>/gemini/v1beta/models/gemini-3-flash:generateContent
→ https://<branch-host>/gemini/v1beta/models/gemini-3-flash:streamGenerateContent

When calling the REST API directly, the model ID and action must appear in the path as shown above.

Error handling

Status	Message	Cause
`400 Bad Request`	`unknown model "<model-id>"`	Model ID not in the catalog
`400 Bad Request`	`model "<model-id>" is not available on the gemini_generate_content endpoint`	Non-Google model sent to this endpoint
`404 Not Found`	`unsupported gemini action`	Action other than `generateContent` or `streamGenerateContent` in URL
`404 Not Found`	`invalid gemini model path`	Malformed `model:action` segment in URL

For authentication, quota, and upstream errors, see Troubleshooting.

Next steps

Models: full model catalog
Chat completions: use Gemini models via the unified OpenAI-compatible endpoint
Authentication: credential scopes and branch binding

Need help?

Join our Discord Server to ask questions or see what others are doing with Neon. For paid plan support options, see Support.