MODELS / CALLSTACK

Apex

Apex is Callstack’s agentic coding model for mobile and web development, optimized for React Native, React, and Next.js. With a 256K context window, it supports feature development, debugging, code reviews, testing, and large refactors.

START BUILDING COMPARE

TEXTREASONINGIMPLICIT-CACHINGREASONINGVISIONTOOL-USE

262.1K

CONTEXT WINDOW

131.1K

MAX OUTPUT TOKENS

$0.5

INPUT PRICE / 1M TOKENS

OUTPUT PRICE / 1M TOKENS

QUICKSTART

Call it in one request.

OpenAI-compatible: change the base URL, and the setup is complete.

curl https://enterprise.blackbox.ai/v1/chat/completions \
  -H "Authorization: Bearer $BLACKBOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "blackboxai/callstack/apex",
    "messages": [{ "role": "user", "content": "Hello!" }],
    "stream": true
  }'

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ.get("BLACKBOX_API_KEY"),
    base_url="https://enterprise.blackbox.ai/v1",
)

stream = client.chat.completions.create(
    model="blackboxai/callstack/apex",
    messages=[{"role": "user", "content": "Hello!"}],
    stream=True,
)

for chunk in stream:
    print(chunk.choices[0].delta.content or "", end="", flush=True)

import OpenAI from 'openai';

const client = new OpenAI({
  apiKey: process.env.BLACKBOX_API_KEY,
  baseURL: 'https://enterprise.blackbox.ai/v1',
});

const stream = await client.chat.completions.create({
  model: 'blackboxai/callstack/apex',
  messages: [{ role: 'user', content: 'Hello!' }],
  stream: true,
});

for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content || '');
}

SPECIFICATIONS

The full spec sheet.

Context, pricing, modalities, routing, and deployment: everything Apex supports, in one table.

MODEL ID: blackboxai/callstack/apex
DEVELOPED BY: Callstack
MODEL TYPE: Text
RELEASED: Oct 8, 2026
CONTEXT WINDOW: 262.1K
MAX OUTPUT TOKENS: 131.1K
INPUT MODALITIES: text, image
OUTPUT MODALITIES: text
INPUT PRICE: $0.5 / 1M tokens
OUTPUT PRICE: $3 / 1M tokens
CACHE READ: $0.2 / 1M tokens
REASONING: Supported
DATA RETENTION: Standard retention
DEDICATED DEPLOYMENT: Not available (closed-weight model)
SUPPORTED PARAMETERS: max_tokenstemperaturestoptoolstool_choicereasoninginclude_reasoning