GPT-5.5 vs Claude Opus 4.7: Which AI Flagship Actually Wins?

OpenAI shipped GPT-5.5 on April 23, 2026. Anthropic shipped Claude Opus 4.7 on April 16. Seven days apart, both with 1M-token context windows, both positioned as their lab's smartest model ever. The era where one model clearly dominated is over — the right choice now depends entirely on what you're using it for.

We've spent the past week testing both across real workflows: coding, writing, data analysis, document review, and general knowledge work. Here's what we found.

What Are the Headline Differences?

Which One Is Better for Coding?

It depends on what kind of coding. GPT-5.5 dominates agentic coding — tasks where the AI needs to plan, execute multiple steps, use terminal commands, and iterate autonomously. It scored 82.7% on Terminal-Bench 2.0 compared to Opus 4.7's 69.4%. For long-running Codex sessions where the model operates independently for minutes at a time, GPT-5.5 is noticeably better at staying on track.

Opus 4.7, however, leads on structured code review and multi-file refactoring. Its SWE-bench Verified score of 87.6% reflects its ability to understand large codebases and make precise, correct changes. Developers working in Claude Code report that Opus 4.7 "catches its own logical faults during the planning phase" — a behavior not seen in previous Claude models.

Which One Writes Better?

Opus 4.7 continues Claude's advantage in writing quality. The prose is more natural, more varied, and closer to how a skilled human would write. GPT-5.5 has improved significantly over GPT-5.4 — OpenAI's president Greg Brockman specifically called out that it's "more intuitive" — but side-by-side, Claude's writing still has more range and less of the formulaic quality that ChatGPT users have complained about for years.

Community sentiment on Reddit around GPT-5.4 (the previous version) included recurring complaints about an "oversmart vibe" and writing that feels over-engineered. Early GPT-5.5 reactions suggest the tone has improved, but Claude's writing advantage persists — particularly for long-form content, emails, and anything where the reader would notice generic phrasing.

Which One Handles Documents and Vision Better?

Opus 4.7 wins here decisively. Its high-resolution vision support handles images up to 3.75 megapixels — roughly 3.3x the resolution of previous Claude models and significantly higher than GPT-5.5's vision capabilities. For tasks involving dense financial charts, multi-column PDFs, architecture diagrams, or annotated screenshots, Opus 4.7 produces noticeably more accurate results.

For document analysis specifically, both models now support 1M token contexts. But Opus 4.7 has historically been more precise at quoting and referencing specific sections within long documents, and early reports suggest this advantage continues with the 4.7 release.

Which One Is Cheaper?

Both charge $5 per million input tokens. Opus 4.7 is cheaper on output: $25 vs GPT-5.5's $30 per million output tokens — a 17% difference. However, GPT-5.5 claims significantly better token efficiency, meaning it uses fewer tokens to complete the same task. OpenAI's data shows GPT-5.5 handles tasks at the same difficulty faster than GPT-5.4 while using fewer tokens.

There's a catch on the Opus side too: Opus 4.7 uses a new tokenizer that can generate 1–1.35x more tokens for the same input compared to Opus 4.6. So while the per-token price is lower, you might use more tokens per request.

For consumer subscriptions, both are $20/month for their respective paid tiers (ChatGPT Plus and Claude Pro). At this level, pricing is identical.

What About Agentic Tasks and Computer Use?

GPT-5.5 is specifically optimized for agentic workflows — tasks where the AI operates autonomously over multiple steps: browsing the web, using software, executing code, and iterating until a task is complete. OpenAI has invested heavily in Codex integration, and GPT-5.5 is the first model where "give it a messy, multi-part task and trust it to figure it out" actually works reliably for most users.

Opus 4.7 introduced task budgets — a feature that gives the model a token budget for an entire agentic loop, letting it plan and prioritize work within that budget. This is a more structured approach to agentic work compared to GPT-5.5's more autonomous style. Both approaches work; they just feel different to use.

What About Safety and Refusals?

Both models ship with stronger safety systems than their predecessors. GPT-5.5 is classified as "High" risk under OpenAI's Preparedness Framework for cybersecurity capabilities — a step up from GPT-5.4. OpenAI warns that the stricter classifiers may feel annoying initially for some users.

Opus 4.7 follows instructions more literally than any previous Claude model. Anthropic explicitly flags this as a behavioral change: prompts that relied on loose interpretation in earlier models may produce different results because Opus 4.7 takes wording at face value. This is a feature, not a bug — but it means existing prompts may need updating.

So Which One Should You Use?

The bottom line: There is no single best model in April 2026. GPT-5.5 and Opus 4.7 are optimized for fundamentally different workflows. Picking the wrong one means paying more for worse results on your specific tasks. Pick by task type, not by brand loyalty.

Using both platforms daily? Managing conversations across ChatGPT and Claude gets messy fast. A cross-platform tool like TresPrompt adds search and folder organization to both from a single Chrome extension — useful when you're switching between models multiple times per day.