# Apex

> Apex is a cost-effective, general-purpose agentic coding model built by Callstack for mobile and web development. It handles everyday agent work across any stack, and it is strongest where React runs — React Native on mobile, Next.js on the web. On React Native tasks it scores above GPT 6.1 Sol and within a point of Claude Opus 5.5 at a fraction of the cost, and on Next.js tasks it matches the best published score at a fraction of the cost per task. It works as a drop-in endpoint for the coding tools teams already use — Claude Code, Cursor, Codex, and others.

Apex is not a single-framework model. It is a general-purpose model that a React Native consultancy trained and keeps current, so the depth shows up where that knowledge is densest: React Native's ecosystem (documentation, public API surface, native modules, build and upgrade paths, conventions grounded in real repositories) and, because it is React, Next.js and React on the web. Everyday backend, TypeScript, infrastructure, and general engineering work is well covered too.

It is reached through an OpenAI- and Anthropic-compatible API, so most tools take it as a config change. It has a 256K context window. Frontier models still perform better on broad general-knowledge tasks, so teams typically make Apex the default for everyday work and for anything in React, and keep a frontier model for the occasional task that needs broader knowledge.

It targets the pain points of using frontier models for daily agent work: outdated library and API choices, rising costs across high-volume agent tasks, and security or data-location limits. It stays sharp across everyday development, large refactors, reviews, tests, and upgrades.

## Access

- [Sign up](https://platform.callstack.ai/signup) — create a business account and get an API key
- [Sign in](https://platform.callstack.ai/signin) — existing accounts
- [Contact](https://apex.callstack.com/contact) — custom enterprise pricing and help setting up self-hosted infrastructure
- [Status](https://status.callstack.ai) — live uptime for the API, platform, and inference engine
- [Models](https://apex.callstack.com/models) — model IDs, pinned snapshots, context window, processing location, and deprecation schedule
- [Discord](https://discord.gg/gkQrpUkryH) — community support channel

## Pricing

All prices are in USD (US dollars) and exclude applicable taxes. Apex is currently available to business accounts only.

- API access: $0.50 / 1M input tokens, $0.20 / 1M cached input tokens, $3.00 / 1M output tokens, pay for actual usage
- On-premise: custom quote, dedicated or on-premise deployments for teams with stricter infrastructure, security, or legal requirements — [contact Callstack](https://apex.callstack.com/contact)

## Performance

React Native ([source](https://rn-evals.vercel.app)):

- Quality: 87.8% for Apex, against 88.6% for Claude Opus 5.5 and 86.3% for GPT 6.1 Sol
- Estimated cost of a full run: $7.72 for Apex, against $11.50 for GPT 6.1 Sol and $28.75 for Claude Opus 5.5 (3.7x cheaper than Opus 5.5, 1.5x cheaper than GPT 6.1 Sol)

Next.js ([source](https://nextjs.org/evals), Sep 25, 2026, 31 tasks, pass@4):

- Quality: 96.8% for Apex with Next.js docs in context, the leaderboard's best score, equal to GPT 6 Astra and Claude Opus 5.5. Without docs Apex scores 90.3%, the same as GPT 6 Astra; Claude Opus 5.5 scores 96.8%
- Cost per task: about $0.067 for Apex, against $0.234 for Claude Opus 5.5 and $0.891 for GPT 6 Astra. Apex's figure is an estimate from the token usage of its published runs; other models use the leaderboard's figures

Throughput: up to 250 tokens/s, up to 3x faster than GPT 6.1 Sol.

## Tools

Works with Claude Code, Cursor, OpenCode, Codex, VS Code, and GitHub Copilot.

## Where it is strongest

- React Native — the deepest capability, including native modules, builds, and upgrades
- Next.js and React on the web, with published Next.js eval results
- General software engineering, agentic workflows, refactors, reviews, tests

## Deployment and security

- Hosted in the EU, with zero data retention enabled by default; customer requests are not kept for later model training
- SOC 2-compliant infrastructure
- Security review ready: enterprise customers can receive a security package and Data Processing Agreement
- Dedicated or on-premise deployment available, in a dedicated environment, your cloud, or your data center

## About

Apex is built by [Callstack](https://callstack.com), a React Native consultancy and open-source contributor.