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Use this how-to guide after the quickstart, when you are ready to put Phaseo behind a real application feature. By the end, you should have:
  • a safely stored API key
  • a clear endpoint choice
  • one working request in your app
  • links to the right production guides for routing, SDKs, and operations

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Before you begin

Make sure you have the following in place:
  • A Phaseo account with Gateway access.
  • An API key from the dashboard.
  • An HTTP client, OpenAI-compatible SDK, or Phaseo SDK.
  • A supported model ID, such as google/gemma-3-27b:free for a zero-credit start.

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1. Store the API key

  1. Open Gateway -> API Keys in the Phaseo dashboard.
  2. Create a key with a name that identifies the app and environment.
  3. Store the value in a secret manager or local environment file:
# .env
PHASEO_API_KEY="phaseo_v1_sk_<kid>_<secret>"
Use separate keys for local development, preview deployments, and production. It makes rotation and usage review much easier.

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2. Choose the endpoint

Choose the endpoint that best matches the job you are doing:
EndpointWhen to use it
/v1/responsesNew text builds, structured outputs, and multi-step workflows.
/v1/chat/completionsChat interfaces, assistants, and OpenAI-style integrations.
/v1/messagesAnthropic-compatible integrations.
/v1/moderationsSafety and content policy checks.
/v1/images/generationsImage generation from text prompts.
Refer to the API Reference for the complete list of supported parameters and responses.
Free-model IDs end with :free and can be called without depositing credits. Paid-model calls require available wallet balance.

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3. Send the app request

Start with the request shape your app is most likely to keep. This example uses Chat Completions because it works well for OpenAI-compatible clients. 
curl https://api.phaseo.ai/v1/chat/completions \
  -H "Authorization: Bearer $PHASEO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "google/gemma-3-27b:free",
    "messages": [
      { "role": "system", "content": "You are a helpful assistant." },
      { "role": "user", "content": "Explain the benefits of AI." }
    ]
  }'

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.PHASEO_API_KEY,
  baseURL: "https://api.phaseo.ai/v1",
});

const response = await client.chat.completions.create({
  model: "google/gemma-3-27b:free",
  messages: [
    { role: "system", content: "You are a helpful assistant." },
    { role: "user", content: "Explain the benefits of AI." },
  ],
});

console.log(response.choices[0]?.message?.content);

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://api.phaseo.ai/v1",
)

response = client.chat.completions.create(
    model="google/gemma-3-27b:free",
    messages=[
        {"role": "system", "content": "You are a helpful assistant."},
        {"role": "user", "content": "Explain the benefits of AI."},
    ],
)

print(response.choices[0].message.content)

package main

import (
  "context"
  "fmt"

  phaseo "github.com/phaseoteam/Phaseo/packages/sdk/sdk-go"
)

func main() {
  client := phaseo.New("YOUR_API_KEY", "https://api.phaseo.ai/v1")

  response, err := client.ChatCompletions(context.Background(), map[string]interface{}{
    "model": "google/gemma-3-27b:free",
    "messages": []map[string]string{
      {"role": "system", "content": "You are a helpful assistant."},
      {"role": "user", "content": "Explain the benefits of AI."},
    },
  })
  if err != nil {
    panic(err)
  }

  fmt.Println(response)
}

using PhaseoSdk;
using System.Collections.Generic;

var client = new Phaseo("YOUR_API_KEY");

var response = await client.ChatCompletions(new Dictionary<string, object>
{
    ["model"] = "google/gemma-3-27b:free",
    ["messages"] = new object[]
    {
        new Dictionary<string, object> { ["role"] = "system", ["content"] = "You are a helpful assistant." },
        new Dictionary<string, object> { ["role"] = "user", ["content"] = "Explain the benefits of AI." }
    }
});

Console.WriteLine(response);

<?php
require 'vendor/autoload.php';

use Phaseo\Sdk\Phaseo;

$client = new Phaseo(getenv('PHASEO_API_KEY') ?: 'YOUR_API_KEY');

$response = $client->chatCompletions([
    'model' => 'google/gemma-3-27b:free',
    'messages' => [
        ['role' => 'system', 'content' => 'You are a helpful assistant.'],
        ['role' => 'user', 'content' => 'Explain the benefits of AI.'],
    ],
]);

print_r($response);

require 'phaseo_sdk'

client = PhaseoSdk::Phaseo.new(api_key: ENV.fetch('PHASEO_API_KEY', 'YOUR_API_KEY'))

response = client.chat_completions(
  model: 'google/gemma-3-27b:free',
  messages: [
    { role: 'system', content: 'You are a helpful assistant.' },
    { role: 'user', content: 'Explain the benefits of AI.' }
  ]
)

puts response

​
4. Configure environments

Store your API key in environment variables for different environments: 
# .env.local
PHASEO_API_KEY="phaseo_v1_sk_<kid>_<secret>"
PHASEO_BASE_URL="https://api.phaseo.ai/v1"
When making requests, send the key in the Authorization header: 
Authorization: Bearer $PHASEO_API_KEY

​
5. Production next steps

Last modified on July 9, 2026