DeepSeek V3.1 vs Grok Code Fast 1

Walkthrough (scores are from our 12-test suite). DeepSeek V3.1 wins 6 benchmarks: faithfulness 5 vs 4 (DeepSeek tied for 1st of 55 models), structured_output 5 vs 4 (DeepSeek tied for 1st of 54), long_context 5 vs 4 (DeepSeek tied for 1st of 55), persona_consistency 5 vs 4 (DeepSeek tied for 1st of 53), creative_problem_solving 5 vs 3 (DeepSeek tied for 1st of 54), and strategic_analysis 4 vs 3 (DeepSeek ranks 27 of 54). What that means: DeepSeek is stronger when you need strict JSON/schema adherence, accurate extraction from very long documents, faithful summarization and consistent personas, and non-obvious ideation. Grok Code Fast 1 wins 4 benchmarks: tool_calling 4 vs 3 (Grok ranks 18 of 54 vs DeepSeek rank 47), agentic_planning 5 vs 4 (Grok tied for 1st of 54), classification 4 vs 3 (Grok tied for 1st of 53), and safety_calibration 2 vs 1 (Grok rank 12 vs DeepSeek 32). That indicates Grok is measurably better for selecting and sequencing function calls, goal decomposition and failure recovery, routing/classification tasks, and more calibrated refusals. Two tests tie: constrained_rewriting 3/3 and multilingual 4/4. In practice: pick DeepSeek for long-document QA, schema-driven outputs, and creative problem solving; pick Grok for agentic coding, tool integrations, and production classifiers where function selection and refusal behavior matter.

Costs are explicit: DeepSeek V3.1 charges $0.15 per 1k input tokens and $0.75 per 1k output tokens; Grok Code Fast 1 charges $0.20 per 1k input and $1.50 per 1k output. Per 1M tokens this is $150 input / $750 output for DeepSeek and $200 input / $1,500 output for Grok. Under a 50/50 input/output split that equals $450/month per 1M tokens for DeepSeek vs $850/month for Grok; at 10M tokens/month that's $4,500 vs $8,500; at 100M tokens/month it's $45,000 vs $85,000. The output-cost gap matters most for output‑heavy applications (document generation, long-form chat); teams doing high-volume agentic coding or tooling should budget the ~2x output cost of Grok or optimize prompts to reduce output tokens with Grok if they need its tool-calling strengths.

Choose DeepSeek V3.1 if you need best-in-class faithfulness, long-context retrieval, structured/JSON outputs, or creative problem solving at a lower cost (wins 6 of 12 benchmarks, many at 5/5). Choose Grok Code Fast 1 if your primary need is agentic coding, reliable tool/function calling, or classification and you accept roughly 2x output token cost for those strengths.