Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
DeepSeek V4 Flash (Max)
77
GPT-5.3 Codex
88
Verified leaderboard positions: DeepSeek V4 Flash (Max) #12 · GPT-5.3 Codex unranked
Pick GPT-5.3 Codex if you want the stronger benchmark profile. DeepSeek V4 Flash (Max) only becomes the better choice if coding is the priority or you want the cheaper token bill.
Agentic
+8.2 difference
Coding
+10.6 difference
DeepSeek V4 Flash (Max)
GPT-5.3 Codex
$0.14 / $0.28
$1.75 / $14
N/A
79 t/s
N/A
88.26s
1M
400K
Pick GPT-5.3 Codex if you want the stronger benchmark profile. DeepSeek V4 Flash (Max) only becomes the better choice if coding is the priority or you want the cheaper token bill.
GPT-5.3 Codex is clearly ahead on the provisional aggregate, 88 to 77. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.3 Codex's sharpest advantage is in agentic, where it averages 71.5 against 63.3. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 56.9% to 77.3%. DeepSeek V4 Flash (Max) does hit back in coding, so the answer changes if that is the part of the workload you care about most.
GPT-5.3 Codex is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash (Max). That is roughly 50.0x on output cost alone. DeepSeek V4 Flash (Max) gives you the larger context window at 1M, compared with 400K for GPT-5.3 Codex.
GPT-5.3 Codex is ahead on BenchLM's provisional leaderboard, 88 to 77. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 56.9% and 77.3%.
DeepSeek V4 Flash (Max) has the edge for coding in this comparison, averaging 73.7 versus 63.1. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
GPT-5.3 Codex has the edge for agentic tasks in this comparison, averaging 71.5 versus 63.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
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