Apex

callstack/apex

A chat model with a 262K-token context window, at $0.525 per million input tokens and $3.15 per million output tokens.

Details

Maker: callstack
Kind: Chat
Context window: 262,144 tokens
Max output: 131,072 tokens
Input: $0.525 per million tokens
Cached input: $0.21 per million tokens, 60% off
Cache write: Same as input
Output: $3.15 per million tokens
Capabilities: Reasoning, tool use, vision
Takes: Text, image
Returns: Text
Zero data retention: Not on every provider
No training on requests: Not on every provider
Released: 2026-10-08

Description

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.

Call it

curl

curl https://phantom.codes/v1/chat/completions \
  -H "Authorization: Bearer $PHANTOM_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "callstack/apex",
    "messages": [
      {"role": "user", "content": "Hello"}
    ]
  }'

Set PHANTOM_KEY to your key. Any OpenAI client works with the base URL https://phantom.codes/v1.

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