Benchmark-backed ChatGPT alternatives ranked by performance, price, context window, and open-weight availability.
Most ChatGPT alternative searches are really about tradeoffs: lower cost, better coding, or more deployment control. BenchLM ranks alternatives against a tracked OpenAI reference using benchmark performance first, then token price, context window, and open-weight availability.
BenchLM uses GPT-5.5 as the tracked OpenAI reference for ChatGPT-like performance.
Direct answer
Claude Sonnet 5 is a strong ChatGPT alternative. It beats GPT-5.5 on BenchLM's general use score. Its blended token price is about 66% lower than GPT-5.5.
Anthropic · Proprietary · 1M context
Claude Sonnet 5 is a strong ChatGPT alternative. It beats GPT-5.5 on BenchLM's general use score. Its blended token price is about 66% lower than GPT-5.5.
BenchLM fit
85.7
Score vs ref
107%
Token cost
66% cheaper
Z.AI · Open Weight · 1M context
GLM-5.2 is a strong ChatGPT alternative. It retains about 99% of GPT-5.5's general use benchmark profile. Its blended token price is about 84% lower than GPT-5.5. It is also open-weight, so you can self-host or fine-tune it.
BenchLM fit
84.9
Score vs ref
99%
Token cost
84% cheaper
Google · Proprietary · 1M context
Gemini 3.6 Flash is a strong ChatGPT alternative. It beats GPT-5.5 on BenchLM's general use score. Its blended token price is about 75% lower than GPT-5.5.
BenchLM fit
84.5
Score vs ref
~103%
Token cost
75% cheaper
Anthropic · Proprietary · 1M context
Claude Opus 4.8 is a strong ChatGPT alternative. It beats GPT-5.5 on BenchLM's general use score.
BenchLM fit
83.1
Score vs ref
111%
Token cost
15% cheaper
Moonshot AI · Pending · 1.05M context
Kimi K3 is a strong ChatGPT alternative. It beats GPT-5.5 on BenchLM's general use score. Its blended token price is about 49% lower than GPT-5.5. It adds a larger 1.05M context window than the tracked ChatGPT reference.
BenchLM fit
82.9
Score vs ref
~104%
Token cost
49% cheaper
DeepSeek · Open Weight · 1M context
DeepSeek V4 Pro (Max) is a strong ChatGPT alternative. It retains about 91% of GPT-5.5's general use benchmark profile. Its blended token price is about 97% lower than GPT-5.5. It is also open-weight, so you can self-host or fine-tune it.
BenchLM fit
82.1
Score vs ref
91%
Token cost
97% cheaper
BenchLM does not treat an alternative query like a generic leaderboard. This page starts from the tracked GPT-5.5 reference, then weights benchmark quality, token cost, context window, and deployment model to find realistic replacements.
That means a model can outrank the absolute leaderboard leader here if it stays close enough on benchmarks while being materially cheaper, more open, or better matched to the workflow implied by the query.
Change the goal, use case, or minimum context if this landing page is close but not exact.
Compare pricingSee the head-to-head comparisonBenchmarks and pricing move fast. We send updates when the rankings shift materially.
One email each week. Unsubscribe anytime.
Claude Sonnet 5 is the current top pick on this page. It scores 79 in the selected BenchLM use-case weighting and 107% of GPT-5.5's benchmark profile, with 66% cheaper as the pricing summary.
Ornith-1.0-397B is the best low-cost candidate surfaced by this page. It ranks as a serious replacement while landing at 100% cheaper than the tracked GPT-5.5 reference.
Yes. GLM-5.2 is the strongest open-weight option on this page. BenchLM surfaces it because it combines self-hostable deployment with a 73 weighted score and 1M of context.
BenchLM uses GPT-5.5 as the tracked ChatGPT reference here, then scores alternatives from benchmark performance first. Token cost, context window, and open-weight preference are used to break ties and surface better real-world replacements rather than just the raw leaderboard winner.