A pelican for GPT-5.5 via the semi-official Codex backdoor API

📰 Simon Willison's Blog

Use the semi-official Codex backdoor API to access GPT-5.5 via the llm-openai-via-codex plugin

advanced Published 23 Apr 2026

Action Steps

Install the llm-openai-via-codex plugin to utilize your existing Codex subscription
Run prompts using the plugin to access GPT-5.5
Use the OpenClaw backdoor to integrate with OpenAI's Codex-specific APIs
Experiment with the pelican benchmark to evaluate the performance of GPT-5.5
Configure the Codex CLI tool to work with your subscription and the llm-openai-via-codex plugin

Who Needs to Know This

Developers and researchers working with AI models, particularly those interested in accessing GPT-5.5 via APIs, can benefit from this information to integrate the model into their projects and workflows.

Key Insight

💡 The semi-official Codex backdoor API provides a way to access GPT-5.5, and the llm-openai-via-codex plugin simplifies this process by leveraging existing Codex subscriptions.