Base44 Adds GPT-5.5 to AI App Builder Chat
Base44Base44 added GPT-5.5 — OpenAI's first fully retrained base model since GPT-4.5 — as a selectable model in its AI chat interface. The model is positioned as a strong choice for complex reasoning and multi-step planning, with improved accuracy and consistency across large or evolving projects. This addition brings Base44's total model roster to seven, spanning both Anthropic and OpenAI flagship models.
Sources & Mentions
5 external resources covering this update
Base44: GPT-5.5 is now available on Base44
X (Twitter)
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OpenAI's GPT-5.5 is here, and it's no potato: narrowly beats Anthropic's Claude Mythos Preview on Terminal-Bench 2.0
VentureBeat
OpenAI upgrades ChatGPT and Codex with GPT-5.5: 'a new class of intelligence for real work'
9to5Mac
AINews: GPT-5.5 and OpenAI Codex Superapp
Latent Space
GPT-5.5 Joins Base44's AI Model Lineup
Base44 expanded its AI chat options on April 24, 2026, making GPT-5.5 available as a selectable model for app-building sessions. The addition comes one day after OpenAI's official release of GPT-5.5 into its API — placing Base44 among the earliest no-code platforms to offer the model.
What GPT-5.5 Brings to Base44
GPT-5.5 is described by Base44 as "a strong choice for complex reasoning and multi-step planning, with improved accuracy and consistency across large or evolving projects." In practical terms, this means the model is well-suited to app-building scenarios where prompts are long and detailed, the codebase is growing, or the builder is iterating through multiple steps of a feature.
OpenAI positioned GPT-5.5 as the first fully retrained base model since GPT-4.5 — unlike GPT-5.1 through GPT-5.4, which were post-training iterations on the same base. The model supports a 1M token context window and leads the field on complex reasoning benchmarks.
Choosing the Right Model
With GPT-5.5 added, Base44 now offers seven model options across both Anthropic and OpenAI families (available to Builder plan subscribers and above):
- Gemini 3.1 Pro — best for logic-heavy and code-heavy work involving visuals, structured data, or multiple files
- Sonnet 4.6 — a balanced choice for everyday development tasks
- Opus 4.6 — recommended for deep debugging and architectural decisions
- Opus 4.7 — the most advanced reasoning model for the hardest problems
- GPT-5.4 — suited to long, detailed prompts and large codebases
- GPT-5.5 — strong at complex reasoning and multi-step planning across large or evolving projects
- GPT-5 — stability-focused reasoning and planning
Base44 also offers three chat modes that work across all models: Default (immediate execution), Discuss (brainstorming without applying changes, at 0.3 credits per message), and Edit (visual design modifications with undo/redo support).
Why This Matters for App Builders
The addition of GPT-5.5 is particularly relevant for Base44 users working on larger, more complex projects — multi-module apps with interconnected database schemas, multi-step agent workflows, or apps that have evolved significantly through many chat iterations. Previous OpenAI options on Base44 (GPT-5.4 and GPT-5) are strong general-purpose choices, but GPT-5.5's full retraining and improved consistency make it a meaningful upgrade for power users tackling ambitious builds.