GPT-5.3 Codex
GPT-5.3 Codex is served by 1 provider that kRouter can route to, with a 400K-token context window and pricing from $3.00 per 1M input tokens. Routing through kRouter means any OpenAI-compatible tool can reach it, with failover to another model if the provider is rate limited.
How to route to GPT-5.3 Codex
| Provider | Route as |
|---|---|
| Cline | cl/openai/gpt-5.3-codex |
What GPT-5.3 Codex is suited for
A 400K window is large enough to hold a substantial part of a codebase in one turn, so it suits whole-repo refactors and long agent sessions where the history keeps growing. It supports extended reasoning, which helps on debugging and multi-step planning but spends output tokens on thinking before the answer appears — worth knowing when you set max_tokens. Tool and function calling are supported, so it can drive an agent loop. Cached input is billed at $1.50 against $3.00 fresh, which is the difference that matters most for agent work — the same context is resent on every turn.
Specs
- Context window
- 400K
- Max output
- 128K
- Input / 1M
- $3.00
- Output / 1M
- $12.00
- Extended reasoning
- Tool / function calling
Cheaper alternatives to GPT-5.3 Codex
Comparable capabilities at a lower rate. With a kRouter combo you can send routine turns to one of these and reserve GPT-5.3 Codex for the work that actually needs it.
- Gemini 2.5 Pro$2.00 in · $12.00 out per 1M
- Gemini 3 Pro Preview$2.00 in · $12.00 out per 1M
- Gemini 3.1 Pro (Low)$2.00 in · $12.00 out per 1M
- Kimi K2.5$1.20 in · $4.80 out per 1M
GPT-5.3 Codex FAQ
How much does GPT-5.3 Codex cost?
GPT-5.3 Codex is $3.00 per 1M input tokens and $12.00 per 1M output tokens. Cached input is $1.50, which matters a lot for agent work that resends the same context each turn.
Which providers serve GPT-5.3 Codex?
Cline serves it. kRouter routes to it as cl/openai/gpt-5.3-codex.
What is GPT-5.3 Codex's context window?
400K tokens, with up to 128K tokens of output. kRouter publishes this on /v1/models as context_length, so clients read the real number instead of guessing from the model name.
Is there a cheaper alternative to GPT-5.3 Codex?
Yes — Gemini 2.5 Pro ($2.00/1M in), Gemini 3 Pro Preview ($2.00/1M in), Gemini 3.1 Pro (Low) ($2.00/1M in), Kimi K2.5 ($1.20/1M in) are cheaper with comparable capabilities. A kRouter combo can send routine turns to one of those and keep GPT-5.3 Codex for the work that needs it.
Route to GPT-5.3 Codex from any tool
kRouter runs locally and gives Claude Code, Cursor, Codex and the rest one endpoint that reaches every provider above — with automatic failover. Free and MIT-licensed.
Install kRouter