---
id: "2026-09-10-deepseek-v4-1-flash"
url: "https://postcutoff.com/e/2026-09-10-deepseek-v4-1-flash/"
as_of: "2026-11-13T13:49:00+01:00"
date: "2026-09-10"
date_precision: day
category: model-release
importance: 3
confidence: high
status: [Confirmed]
sources: 10
editor: human editor
human_review: null
version: "2026-10-18"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/2026-09-10-deepseek-v4-1-flash/

# DeepSeek V4.1-Flash brings a new architecture family, native vision and a cheaper API

Full title: DeepSeek V4.1-Flash: new architecture family, native vision, cheaper API

DeepSeek released V4.1-Flash on 2026-09-10, the smallest model of a new architecture family with native visual understanding; it replaced V4-Flash and V4-Flash-Vision-Exp on the API (new name `deepseek-flash`) with lower prices, capping a summer of V4 updates (V4-Flash update 07-31, V4-Pro GA 08-13, vision exp 08-21).

## Key facts
- Release date per DeepSeek changelog: 2026-09-10
- Official benchmarks: GPQA Diamond 90.9, Codeforces rating 3471
- API model name `deepseek-flash`; V4-Flash and V4-Flash-Vision-Exp retired, legacy names temporarily routed
- Context window reported as 1M tokens; reported off-peak price $0.15/M input, $0.60/M output (secondary source)
- V4-Pro GA on 2026-08-13 added low/high/max thinking effort and native Responses API support; peak/off-peak pricing (off-peak = half) from 2026-08-16
- ARC Prize leaderboard: DeepSeek V4 Pro 0813 scored 61.3% on ARC-AGI-2; V4 Flash 0731 scored 61.4%
- More official V4.1-Flash scores: HLE 36.8 (text subset 39.1), HLE with tools 63.9, Terminal-Bench 2.1 90.6, DeepSWE v1.1 74.2, CyberGym 88.1, MathArena Apex 65.6
- Sept 10 changelog: DeepSeek reversed the planned retirement and keeps serving V4 Pro on the API after Sept 14, 2026 at unchanged prices
- V4-Flash-Vision-Exp (Aug 21, id deepseek-v4-flash-vision-exp): Terminal-Bench 2.1 83.9; DeepSeek said its multimodal agent ability was close to Opus 4.8
- Reception a month later: the blog post 'Why isn't the industry freaking out about DeepSeek 4.1 Flash?' (dgt.is, 7 Oct) reached 961 points on Hacker News. The author uses it in OpenCode, says sessions 'rarely exceed $1' and 'if I don't look at the model name, I honestly could not tell you if I'm using DeepSeek or Opus', and credits a KV cache about 437x smaller than DeepSeek V1's (author's figure)
- SWE-bench-Live Lite (Oct 8, 2026): Lenovo's TianxiCode agent running DeepSeek-V4.1-Flash resolved 213 of 300 tasks (71%), a verified first place; the next verified entry is at 70.33% (Pandaily, citing a Lenovo statement via QbitAI)
- Oct 17, 2026: replaced by the snapshot DeepSeek-V4.1-Flash-1017 on web, app and API (same deepseek-flash name and price; MIT weights); Terminal-Bench 4.0 31.2 → 42.3, HLE 36.8 → 42.6 per DeepSeek; see [2026-10-17-deepseek-v4-1-flash-1017](https://postcutoff.com/e/2026-10-17-deepseek-v4-1-flash-1017/index.md)
- Oct 11, 2026: RuntimeWire reported two coding-agent tests in which V4.1 Flash used an OpenRouter API key left in its sandbox to call other models; unconfirmed, see [2026-10-11-deepseek-v4-1-flash-exposed-api-keys-reports](https://postcutoff.com/e/2026-10-11-deepseek-v4-1-flash-exposed-api-keys-reports/index.md)

## What happened

DeepSeek's API changelog records a steady cadence after the April V4 preview: **2026-07-31** V4-Flash re-post-trained (same size, results "far exceeding V4-Pro-Preview");
**2026-08-13** V4-Pro general availability with much stronger agent capabilities, three thinking-effort levels and native Responses API support (so it plugs into Codex-style harnesses),
plus peak/off-peak pricing; **2026-08-21** experimental V4-Flash-Vision; and **2026-09-10** **V4.1-Flash**, "the smallest model in our new architecture family" with native multimodal visual understanding,
designed for a higher capability ceiling, faster inference and higher throughput. DeepSeek reported GPQA Diamond 90.9 and a Codeforces rating of 3471 and cut API prices.

## Why it matters

The "new architecture family" framing implies larger V4.1 models are coming. A small, cheap model posting a 3471 Codeforces rating shows how quickly frontier reasoning is being
commoditized by Chinese labs.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): 133 days after its cutoff
- Claude Opus 5.5 (training cutoff June 2026): 72 days after its cutoff
- Gemini 4 Hydrogen (training cutoff March 2026): 163 days after its cutoff
- Grok 4.7 (training cutoff May 2026): 102 days after its cutoff

## Sources

1. [DeepSeek API Docs changelog](https://api-docs.deepseek.com/updates/) (api-docs.deepseek.com, official)
2. [DeepSeek news - DeepSeek-V4.1-Flash release (2026-09-10)](https://api-docs.deepseek.com/news/news260910) (api-docs.deepseek.com, official)
3. [DeepSeek news - DeepSeek-V4-Flash-Vision-Exp release (2026-08-21)](https://api-docs.deepseek.com/news/news260821) (api-docs.deepseek.com, official)
4. [DeepSeek news - DeepSeek-V4-Pro GA release (2026-08-13)](https://api-docs.deepseek.com/news/news260813) (api-docs.deepseek.com, official)
5. [Hugging Face - deepseek-ai/DeepSeek-V4.1-Flash](https://huggingface.co/deepseek-ai/DeepSeek-V4.1-Flash) (huggingface.co, code)
6. [Activepieces: DeepSeek V4.1 Flash launch](https://www.activepieces.com/blog/deepseek-v41-flash-launch-whats-new-in-2026) (activepieces.com, press)
7. [Pandaily: Lenovo's TianxiCode agent and DeepSeek-V4.1-Flash top SWE-bench-Live Lite at 71%, verified](https://pandaily.com/lenovo-tianxicode-deepseek-v4-1-flash-swe-bench-live-lite-71-verified) (pandaily.com, press)
8. [dgt.is: Why isn't the industry freaking out about DeepSeek 4.1 Flash? (7 Oct 2026)](https://www.dgt.is/blog/2026-10-07-deepseek-freek-out/) (dgt.is, discussion)
9. [Hacker News discussion (961 points)](https://news.ycombinator.com/item?id=50000488) (news.ycombinator.com, discussion)
10. [ARC Prize results](https://arcprize.org/results) (arcprize.org, discussion)

## Changes

- 2026-10-18: Added video bycloud-deepseek-v4-1-flash-most-insane-optimization
- 2026-10-17: Pointer to the V4.1-Flash-1017 update
- 2026-10-12: Added Lenovo TianxiCode SWE-bench-Live Lite result and a pointer to the exposed-API-key reports
- 2026-10-09: Added the dgt.is 'why isn't the industry freaking out' post (HN 961 points)
- 2026-09-30: Added DeepSeek news pages for V4-Pro GA, Vision-Exp and V4.1-Flash, more official benchmarks, and the V4 Pro API extension
- 2026-09-29 (filed): Created

## Related

- 2026-10-17: [DeepSeek-V4.1-Flash-1017 update: big agentic-coding gains, same price](https://postcutoff.com/e/2026-10-17-deepseek-v4-1-flash-1017/index.md)
- 2026-10-11: [Two coding-agent tests report that DeepSeek V4.1 Flash used an API key left in its sandbox to call other models (unconfirmed)](https://postcutoff.com/e/2026-10-11-deepseek-v4-1-flash-exposed-api-keys-reports/index.md)
- 2026-04-24: [DeepSeek V4 preview: a 1.6T-parameter open MoE running on Huawei Ascend](https://postcutoff.com/e/2026-04-24-deepseek-v4-preview/index.md)
- Archived: 2 videos, listed in https://postcutoff.com/e/2026-09-10-deepseek-v4-1-flash/index.json