Pick Claude Opus 4.6 for agentic coding and debugging in large codebases or long-running, multi-step autonomous agent tasks. Pick GPT-5.5 for terminal, cli and computer-use automation or long-horizon tool sequencing.
Claude Opus 4.6 (Anthropic) and GPT-5.5 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Opus 4.6 is anthropic's February 2026 flagship Opus and the first Opus-class model with a 1M-token context window, built for agentic coding and long-running professional tasks. GPT-5.5 is openAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. The breakdown below works through their capabilities and ideal use cases so you can match one to your task.
Key differences
Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
Recency: GPT-5.5 is the newer model by about 3 months (released April 23, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Claude Opus 4.6
GPT-5.5
Provider
Anthropic (US)
OpenAI (US)
Released
February 5, 2026
April 23, 2026
Context window
1M (~1,500 pages)
1M (~1,500 pages)
Price (in/out)
$5/$25 per 1M tokens
$5/$30 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
80.8%
Not published
MRCR v2 @ 1M
76%
Not published
Who wins what
Agentic coding and debugging in large codebases: Claude Opus 4.6 — A core design strength of Claude Opus 4.6.
Long-running, multi-step autonomous agent tasks: Claude Opus 4.6 — A core design strength of Claude Opus 4.6.
Frontier multidisciplinary reasoning (leads Humanity's Last Exam): Claude Opus 4.6 — A core design strength of Claude Opus 4.6.
Terminal, CLI and computer-use automation: GPT-5.5 — A core design strength of GPT-5.5.
Long-horizon tool sequencing: GPT-5.5 — A core design strength of GPT-5.5.
Strong agentic coding and reasoning: GPT-5.5 — A core design strength of GPT-5.5.
Which should you pick?
Anyone whose priority is agentic coding and debugging in large codebases: Claude Opus 4.6 — It is specifically built for that.
Anyone whose priority is terminal, cli and computer-use automation: GPT-5.5 — That is its strongest area.
Claude Opus 4.6: where it fits
Anthropic's February 2026 flagship Opus and the first Opus-class model with a 1M-token context window, built for agentic coding and long-running professional tasks. Released February 5, 2026 by Anthropic, it is built for agentic coding and debugging in large codebases, long-running, multi-step autonomous agent tasks, frontier multidisciplinary reasoning (leads Humanity's Last Exam), and economically valuable knowledge work in finance and legal (GDPval-AA).
Its trade-offs are real: superseded by newer Claude Opus 4.7 and 4.8 (now a legacy model), and top-tier per-token price, and its 1M-token context shipped as beta. At $5 in / $25 out per million tokens, it sits in the premium price band.
GPT-5.5: where it fits
OpenAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Released April 23, 2026 by OpenAI, it is built for terminal, CLI and computer-use automation, long-horizon tool sequencing, strong agentic coding and reasoning, and browser-driving agents.
Its trade-offs: trails Opus 4.8 on hardest coding benchmarks, and tiered long-context pricing above 272K tokens. At $5 in / $30 out per million tokens, it sits in the premium price band.
The bottom line for this matchup
Claude Opus 4.6 and GPT-5.5 overlap enough that the right pick depends on your specific job. and each leads in its own area — Claude Opus 4.6 for agentic coding and debugging in large codebases, GPT-5.5 for terminal, cli and computer-use automation. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Claude Opus 4.6 or GPT-5.5 better for coding?
Public SWE-Bench figures are not available for GPT-5.5, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 4.6 leans toward agentic coding and debugging in large codebases while GPT-5.5 leans toward terminal, cli and computer-use automation, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Opus 4.6 or GPT-5.5?
They are priced almost identically, so cost will not decide between them.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Claude Opus 4.6 and GPT-5.5 together?
Yes — a multi-model platform like LumiChats gives you Claude Opus 4.6, GPT-5.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Opus 4.6 or GPT-5.5?
GPT-5.5 — released April 23, 2026, about 3 months after Claude Opus 4.6.
Claude Opus 4.6 vs GPT-5.5
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Opus 4.6 for agentic coding and debugging in large codebases or long-running, multi-step autonomous agent tasks. Pick GPT-5.5 for terminal, cli and computer-use automation or long-horizon tool sequencing.
Claude Opus 4.6 (Anthropic) and GPT-5.5 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Opus 4.6 is anthropic's February 2026 flagship Opus and the first Opus-class model with a 1M-token context window, built for agentic coding and long-running professional tasks. GPT-5.5 is openAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. The breakdown below works through their capabilities and ideal use cases so you can match one to your task.
Key differences at a glance
▸Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
▸Recency: GPT-5.5 is the newer model by about 3 months (released April 23, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Claude Opus 4.6
GPT-5.5
Provider
Anthropic (US)
OpenAI (US)
Released
February 5, 2026
April 23, 2026
Context window
1M (~1,500 pages)
1M (~1,500 pages)
Price (in/out)
$5/$25 per 1M tokens
$5/$30 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
80.8%
Not published
MRCR v2 @ 1M
76%
Not published
Who wins what
Agentic coding and debugging in large codebases
Claude Opus 4.6
A core design strength of Claude Opus 4.6.
Long-running, multi-step autonomous agent tasks
Claude Opus 4.6
A core design strength of Claude Opus 4.6.
Frontier multidisciplinary reasoning (leads Humanity's Last Exam)
Claude Opus 4.6
A core design strength of Claude Opus 4.6.
Terminal, CLI and computer-use automation
GPT-5.5
A core design strength of GPT-5.5.
Long-horizon tool sequencing
GPT-5.5
A core design strength of GPT-5.5.
Strong agentic coding and reasoning
GPT-5.5
A core design strength of GPT-5.5.
Which should you pick?
Anyone whose priority is agentic coding and debugging in large codebases
→ Claude Opus 4.6
It is specifically built for that.
Anyone whose priority is terminal, cli and computer-use automation
→ GPT-5.5
That is its strongest area.
Claude Opus 4.6: where it fits
Anthropic's February 2026 flagship Opus and the first Opus-class model with a 1M-token context window, built for agentic coding and long-running professional tasks. Released February 5, 2026 by Anthropic, it is built for agentic coding and debugging in large codebases, long-running, multi-step autonomous agent tasks, frontier multidisciplinary reasoning (leads Humanity's Last Exam), and economically valuable knowledge work in finance and legal (GDPval-AA).
Its trade-offs are real: superseded by newer Claude Opus 4.7 and 4.8 (now a legacy model), and top-tier per-token price, and its 1M-token context shipped as beta. At $5 in / $25 out per million tokens, it sits in the premium price band.
GPT-5.5: where it fits
OpenAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Released April 23, 2026 by OpenAI, it is built for terminal, CLI and computer-use automation, long-horizon tool sequencing, strong agentic coding and reasoning, and browser-driving agents.
Its trade-offs: trails Opus 4.8 on hardest coding benchmarks, and tiered long-context pricing above 272K tokens. At $5 in / $30 out per million tokens, it sits in the premium price band.
The bottom line for this matchup
Claude Opus 4.6 and GPT-5.5 overlap enough that the right pick depends on your specific job. and each leads in its own area — Claude Opus 4.6 for agentic coding and debugging in large codebases, GPT-5.5 for terminal, cli and computer-use automation. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Opus 4.6 and GPT-5.5 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
Public SWE-Bench figures are not available for GPT-5.5, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 4.6 leans toward agentic coding and debugging in large codebases while GPT-5.5 leans toward terminal, cli and computer-use automation, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Opus 4.6 or GPT-5.5?
They are priced almost identically, so cost will not decide between them.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Claude Opus 4.6 and GPT-5.5 together?
Yes — a multi-model platform like LumiChats gives you Claude Opus 4.6, GPT-5.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Opus 4.6 or GPT-5.5?
GPT-5.5 — released April 23, 2026, about 3 months after Claude Opus 4.6.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.