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GPT-5.3 Codex AI Chat Assistant

GPT-5.3 Codex is Rivya's stronger Codex AI coding assistant for multi-file debugging, technical planning, refactor analysis, and codebase-level reasoning before stepping up to GPT-5.4 Codex.

Input
Prompt + optional images
Output
AI Chat Assistant
Credits
Pay per use — credits based on usage
Best for
Hard debugging in large codebases
Example output

Example output

Best for architecture cleanup, boundaries, and avoiding unrelated churn.

Responses

Online trial

Use GPT-5.3 Codex

Input setup

Prepare this run

Estimated credits: 4+

Chat controls

Choose when Rivya can search the web, how much reasoning it should use, and whether to include model thoughts when the selected model supports them.

Web search

Allow supported models to pull live web results during the reply.

Reasoning

Use the model default, or request a stronger or lighter reasoning level when available.

Start a conversation to turn planning, prompting, and creative direction into one reusable thread.

Prompt starters

Start GPT-5.3 Codex with a proven prompt

Use a template already mapped to GPT-5.3 Codex when you want a stronger first run than a blank prompt.

Model proof

What GPT-5.3 Codex output looks like

Use the online trial above, then compare these example results to judge finish, rhythm, and task fit before you spend more credits in Studio.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Chat preview for a Codex refactor scope prompt.

Output

Best for architecture cleanup, boundaries, and avoiding unrelated churn.

Lead sample

Best for architecture cleanup, boundaries, and avoiding unrelated churn.

Chat preview for a Codex refactor scope prompt.

Input

Prompt + optional images

What to notice

Chat preview for a Codex refactor scope prompt.

Credits per use

Pay per use — credits based on usage

Why this model works

Why this model works

OpenAI's most capable code model

State-of-the-art code generation quality

Deepest reasoning for complex problems

Best-fit tasks

Best-fit tasks

Hard debugging in large codebasesComplex implementation plans with tool stepsHigh-stakes code review and regression huntingEnd-to-end feature scaffolding

Model proof

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Multi-Repo Change Plan Chat.

Plan a change that touches multiple repos with order, contracts, verification, and rollback boundaries.

Conversation preview for Multi-Repo Change Plan Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Code Owner Handoff Chat.

Create a code owner handoff with touched files, invariants, known risks, verification, and next owner decision.

Conversation preview for Code Owner Handoff Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Security Review Questions Chat.

Generate security review questions from a feature note, focusing on auth, storage, user data, and abuse paths.

Conversation preview for Security Review Questions Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for CI Failure Triage Chat.

Triage a CI failure by separating changed-file failures, environment failures, flaky tests, and next command.

Conversation preview for CI Failure Triage Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Architecture Tradeoff Record Chat.

Write an architecture tradeoff record with context, options, decision, consequences, and revisit trigger.

Conversation preview for Architecture Tradeoff Record Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Multi-Repo Change Plan Chat.

Plan a change that touches multiple repos with order, contracts, verification, and rollback boundaries.

Conversation preview for Multi-Repo Change Plan Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Code Owner Handoff Chat.

Create a code owner handoff with touched files, invariants, known risks, verification, and next owner decision.

Conversation preview for Code Owner Handoff Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Security Review Questions Chat.

Generate security review questions from a feature note, focusing on auth, storage, user data, and abuse paths.

Conversation preview for Security Review Questions Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for CI Failure Triage Chat.

Triage a CI failure by separating changed-file failures, environment failures, flaky tests, and next command.

Conversation preview for CI Failure Triage Chat.

chat thread

Ask Rivya to help with planning, prompting, analysis, or coding.

Conversation preview for Architecture Tradeoff Record Chat.

Write an architecture tradeoff record with context, options, decision, consequences, and revisit trigger.

Conversation preview for Architecture Tradeoff Record Chat.

Decision fit

When this model is the right choice

Decision fit

Fit signals

OpenAI's most capable code model
State-of-the-art code generation quality
Deepest reasoning for complex problems
12K output tokens with vision support
Best for demanding development projects

Best-fit tasks

Use it when the task looks like this

Hard debugging in large codebasesComplex implementation plans with tool stepsHigh-stakes code review and regression huntingEnd-to-end feature scaffoldingAgentic engineering projects with long context

Quiet facts

Inputs, output, and credits to confirm

Provider

OpenAI

Category

Chat

Capabilities

Responses

Credit model

Pay per use — credits based on usage

Input path

Prompt + optional images

Prompt setup

Up to 20,000 chars

Developer access

Available via API

Call GPT-5.3 Codex from Public API v1 after checking the model fields, reference media rules, and credit behavior.

FAQ

GPT-5.3 Codex FAQ

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