Which is cheaper, GPT-5 or DeepSeek V3?

DeepSeek V3 is the cheaper of the two: one 1,000-word request costs about 579 toman, about 8.7× cheaper than GPT-5.

Can I use GPT-5 and DeepSeek V3 with one API key?

Yes. An uttapen key reaches every model unless you gave it an allowed-models list, and each request is charged in toman to the same wallet; only the model value changes.

GPT-5 vs DeepSeek V3

Both sit behind the same key and the same code on uttapen — the only thing that changes is the model string, so you can run each of them against your own workload without touching anything else. On cost, DeepSeek V3 comes out about 8.7× cheaper.

Feature	GPT-5	DeepSeek V3
Provider	OpenAI	DeepSeek
Model id	openai/gpt-5	deepseek/deepseek-chat
Context	400,000 tokens	163,840 tokens
Max output	128,000 tokens	16,000 tokens
Input / 1M tokens	432,774 toman	89,117 toman
Output / 1M tokens	3,462,194 toman	356,156 toman
≈ one 1,000-word request	5,063 toman	579 toman
Input caching	43,277 toman / 1M	No
Image input	Yes	No
File input	Yes	No
Tool calling	Yes	Yes
JSON output	Yes	Yes
Reasoning mode	Yes	No

Which one for what?

GPT-5

Multi-step problems, maths, and tracking down a bug
Whole documents or a codebase in a single request
Reading screenshots, invoices, and scanned forms
Agents that call your own APIs and database

5,063 toman per 1,000 words · Model page

DeepSeek V3

Agents that call your own APIs and database

579 toman per 1,000 words · Model page

Run both with the same code

Swap the model value between the two ids and send the same request twice; what each answer cost comes back in the X-Uttapen-Cost-Toman header.

curlPythonNode.jsPHPGo

curl https://api.uttapen.ir/v1/chat/completions \
  -H "Authorization: Bearer sk-up-…" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5",
    "messages": [{"role": "user", "content": "Introduce yourself."}],
    "stream": true
  }'

from openai import OpenAI

client = OpenAI(
    base_url="https://api.uttapen.ir/v1",
    api_key="sk-up-…",
)

stream = client.chat.completions.create(
    model="openai/gpt-5",
    messages=[{"role": "user", "content": "Introduce yourself."}],
    stream=True,
)
for chunk in stream:
    print(chunk.choices[0].delta.content or "", end="", flush=True)

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.uttapen.ir/v1",
  apiKey: "sk-up-…",
});

const stream = await client.chat.completions.create({
  model: "openai/gpt-5",
  messages: [{ role: "user", content: "Introduce yourself." }],
  stream: true,
});
for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content ?? "");
}

<?php
// composer require openai-php/client guzzlehttp/guzzle
$client = OpenAI::factory()
    ->withBaseUri('https://api.uttapen.ir/v1')
    ->withApiKey('sk-up-…')
    ->make();

$result = $client->chat()->create([
    'model' => 'openai/gpt-5',
    'messages' => [['role' => 'user', 'content' => 'Introduce yourself.']],
]);
echo $result->choices[0]->message->content;

package main

import (
	"context"
	"fmt"

	"github.com/openai/openai-go"
	"github.com/openai/openai-go/option"
)

func main() {
	client := openai.NewClient(
		option.WithBaseURL("https://api.uttapen.ir/v1"),
		option.WithAPIKey("sk-up-…"),
	)
	resp, err := client.Chat.Completions.New(context.Background(), openai.ChatCompletionNewParams{
		Model:    "openai/gpt-5",
		Messages: []openai.ChatCompletionMessageParamUnion{openai.UserMessage("Introduce yourself.")},
	})
	if err != nil {
		panic(err)
	}
	fmt.Println(resp.Choices[0].Message.Content)
}

model = "deepseek/deepseek-chat"

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Frequently asked

Which is cheaper, GPT-5 or DeepSeek V3?: DeepSeek V3 is the cheaper of the two: one 1,000-word request costs about 579 toman, about 8.7× cheaper than GPT-5.
Which one has the larger context window?: GPT-5, with 400,000 tokens.
Can I use GPT-5 and DeepSeek V3 with one API key?: Yes. An uttapen key reaches every model unless you gave it an allowed-models list, and each request is charged in toman to the same wallet; only the model value changes.

More comparisons: all pairs · model rankings · full catalogue

base_url = https://api.uttapen.ir/v1