Open-weight 1.6T-parameter MoE with 1M-token context and three reasoning modes for coding and long-horizon agents.
Output Speed *
Intelligence Index *
Context Window *
Input price
Output price
Performance
Where V4 Pro 0423 Earns Its Place: Reasoning and Coding at Scale
Benchmarks
V4 Pro 0423 Independent Benchmarks: Intelligence, Long Context, Hallucination
Output Speed
Intelligence Index
MMLU *
GPQA *
HLE *
LiveCodeBench *
Technical Specifications
What the model supports
Comparison
V4 Pro 0423 vs V4 Flash: When You Actually Need the 1.6T Model
V4 Pro 0423 and V4 Flash ship in the same V4 preview release, share the 1M-token context, the same three reasoning modes, and MIT open weights, so switching between them is a model-name change rather than a re-integration. The difference is scale: Pro activates 49B parameters per token from a 1.6T backbone, while Flash activates roughly 13B from 284B total. The practical decision is how much per-token capability a workload genuinely needs versus how much throughput and cost efficiency you want.
Choose V4 Pro 0423 when the work is genuinely hard: repository-scale debugging, complex reasoning, long-horizon agentic investigations, and knowledge-heavy tasks where the larger active-parameter count matters. Choose V4 Flash when responsiveness and cost dominate — routine transformations, summarization, test generation, chat, and high-volume pipelines. Flash reportedly approaches Pro on simple agent tasks and reasoning with a larger thinking budget, so reserve Pro for cases where Flash measurably falls short.
Limitations & Trade-offs
Best-Fit Workloads
Where this model earns its place
Repository-scale coding and refactoring
The 1M-token context lets V4 Pro 0423 ingest full codebases without chunking, and V4-Pro-Max reports 80.6% on SWE-bench Verified. This suits long-horizon debugging, architecture changes, and multi-file refactors where whole-repo awareness matters. Note that independent code testing shows stronger performance on syntax-similarity than on functional correctness for some categories, so keep human review in the loop for production commits.
Long-horizon agentic workflows
V4 Pro supports tool calling inside thinking mode and leads open-weight peers on agentic benchmarks like GDPval-AA. Combined with a large context, this fits tool-heavy investigations, terminal and computer-use agents, and multi-step task automation. Use High effort for routine agent loops and Max only for complex planning, since Max's token volume compounds cost across long agent trajectories.
Long-document analysis and RAG
With a 1M-token window and roughly 83.5 on MRCR 1M retrieval, the model can reason over large document sets in a single pass, reducing chunking complexity in RAG pipelines. It fits legal, financial, and technical document synthesis. Given the high hallucination rate on unknown answers, ground responses in retrieved context and add citation or verification steps for factuality-sensitive outputs.
Complex reasoning and STEM problem-solving
Max reasoning effort scores 45 on the Artificial Analysis Intelligence Index, well above the open-weight median, making V4 Pro 0423 suitable for math, science, and multi-step analytical tasks. It fits research assistants and technical decision-support where depth outweighs latency. Reserve Max for genuinely hard problems and drop to High or Non-Think for simpler queries to control verbosity and response time.