DeepSeek V4.1 Flash vs LongCat-2.5
DeepSeek · China | Meituan · China · Updated June 2026
Quick verdict
Pick DeepSeek V4.1 Flash for software engineering (deepswe v1.1: 74.2, essentially level with claude opus 5's 74.0) or 1m-token context window at a fraction of frontier pricing ($0.15/$0.60 per million tokens off-peak). Pick LongCat-2.5 for native multimodal upgrade to longcat-2.0 - 1.6t total parameters, about 48b active per token or limited-time api price of $0.30/$1.20 per million tokens (cached input $0.006). Choose DeepSeek V4.1 Flash if you need self-hosting or data privacy; LongCat-2.5 if you want a managed API.
DeepSeek V4.1 Flash (DeepSeek) and LongCat-2.5 (Meituan) are two of the models people most often weigh against each other in 2026. DeepSeek V4.1 Flash is deepSeek's September 2026 flash-tier update adds native vision and a 1M-token window to its cost-efficient V4 line, at $0.15/$0.60 per million tokens. LongCat-2.5 is meituan's November 2, 2026 natively multimodal successor to LongCat-2.0 - 1.6T parameters and 1M context at $0.30/$1.20, with open weights planned but undated. They diverge most on price, context window and open vs. closed weights — each quantified below from the models' real specs.
Key differences at a glance
- ▸Price: DeepSeek V4.1 Flash is about 2× cheaper on input ($0.15/$0.6 per 1M tokens vs $0.3/$1.2 per 1M tokens) — meaningful once you are processing millions of tokens a month.
- ▸Context window: 1.05M tokens vs 1M tokens — within a few percent of each other, so treat this as a tie and test on your own long inputs, since usable recall varies by model.
- ▸Recency: LongCat-2.5 is the newer model by about 53 days (released November 2, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | DeepSeek V4.1 Flash | LongCat-2.5 |
|---|---|---|
| Provider | DeepSeek (China) | Meituan (China) |
| Released | September 10, 2026 | November 2, 2026 |
| Context window | 1.05M tokens (~1,573 pages) | 1M tokens (~1,500 pages) |
| Price (in/out) | $0.15/$0.6 per 1M tokens | $0.3/$1.2 per 1M tokens |
| Open weight? | Yes — self-hostable | No — API only |
| Modalities | text, image | text, image, code |
| SWE-Bench Verified | Not published | Not published |
| MRCR v2 @ 1M | Not published | Not published |
Who wins what
Software engineering (DeepSWE v1.1: 74.2, essentially level with Claude Opus 5's 74.0)
DeepSeek V4.1 Flash
DeepSeek's September 2026 flash-tier update adds native vision and a 1M-token window to its cost-efficient V4 line, at $0.15/$0.60 per million tokens — and it runs cheaper at $0.15/$0.6 per 1M tokens.
1M-token context window at a fraction of frontier pricing ($0.15/$0.60 per million tokens off-peak)
DeepSeek V4.1 Flash
DeepSeek's September 2026 flash-tier update adds native vision and a 1M-token window to its cost-efficient V4 line, at $0.15/$0.60 per million tokens — and its weights are open while LongCat-2.5 is API-only.
Native multimodal vision, added over the text-only V4-Flash it replaces on most traffic
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash lists native multimodal vision, added over the text-only V4-Flash it replaces on most traffic among its strengths; LongCat-2.5 does not.
Native multimodal upgrade to LongCat-2.0 - 1.6T total parameters, about 48B active per token
LongCat-2.5
DeepSeek V4.1 Flash is comparatively weak here — new Causal Encoder-Decoder architecture (8B active for input, 16B for output) is unproven at broader scale versus DeepSeek's mainline V4/V4-Pro line
Limited-time API price of $0.30/$1.20 per million tokens (cached input $0.006)
LongCat-2.5
Meituan's November 2, 2026 natively multimodal successor to LongCat-2.0 - 1.6T parameters and 1M context at $0.30/$1.20, with open weights planned but undated — and it is the newer of the two.
Meituan-reported Terminal-Bench v2.1 of 88.4, up from 70.8 for LongCat-2.0
LongCat-2.5
DeepSeek V4.1 Flash is comparatively weak here — the $0.15/$0.60 pricing is an off-peak rate — cost reportedly doubles during peak-demand hours
Lowest cost at scale
DeepSeek V4.1 Flash
At $0.15/$0.6 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume
→ DeepSeek V4.1 Flash
At $0.15/$0.6 per 1M tokens it undercuts LongCat-2.5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ DeepSeek V4.1 Flash
Larger 1.05M tokens window fits more in one prompt.
A team with data-privacy or self-hosting needs
→ DeepSeek V4.1 Flash
Open weights let you run it on your own hardware; LongCat-2.5 is API-only.
Anyone whose priority is software engineering (deepswe v1.1: 74.2, essentially level with claude opus 5's 74.0)
→ DeepSeek V4.1 Flash
It is specifically built for that.
Anyone whose priority is native multimodal upgrade to longcat-2.0 - 1.6t total parameters, about 48b active per token
→ LongCat-2.5
That is its strongest area.
DeepSeek V4.1 Flash: where it fits
DeepSeek's September 2026 flash-tier update adds native vision and a 1M-token window to its cost-efficient V4 line, at $0.15/$0.60 per million tokens. Released September 10, 2026 by DeepSeek, it is built for software engineering (DeepSWE v1.1: 74.2, essentially level with Claude Opus 5's 74.0), 1M-token context window at a fraction of frontier pricing ($0.15/$0.60 per million tokens off-peak), native multimodal vision, added over the text-only V4-Flash it replaces on most traffic, and mIT-licensed open weights, self-hostable.
Its trade-offs are real: the $0.15/$0.60 pricing is an off-peak rate — cost reportedly doubles during peak-demand hours, new Causal Encoder-Decoder architecture (8B active for input, 16B for output) is unproven at broader scale versus DeepSeek's mainline V4/V4-Pro line, and positioned as a cost/speed tier, not a frontier-reasoning flagship — DeepSeek kept V4-Pro running in parallel rather than replacing it outright. At $0.15 in / $0.6 out per million tokens, it sits in the budget price band.
LongCat-2.5: where it fits
Meituan's November 2, 2026 natively multimodal successor to LongCat-2.0 - 1.6T parameters and 1M context at $0.30/$1.20, with open weights planned but undated. Released November 2, 2026 by Meituan, it is built for native multimodal upgrade to LongCat-2.0 - 1.6T total parameters, about 48B active per token, limited-time API price of $0.30/$1.20 per million tokens (cached input $0.006), meituan-reported Terminal-Bench v2.1 of 88.4, up from 70.8 for LongCat-2.0, and openAI- and Anthropic-compatible API endpoints with a 1M-token context window.
Its trade-offs: aPI-only for now - GitHub and Hugging Face releases are planned but undated, and the license is unconfirmed (LongCat-2.0 is MIT), the $0.30/$1.20 rate is labeled limited-time, and Meituan says prices are subject to change, and benchmarks are Meituan's own, and sources found no independent score at launch. At $0.3 in / $1.2 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
The defining split here is open vs. closed. DeepSeek V4.1 Flash gives you weights you control — self-host it, fine-tune it, keep data in-house, pay only for hardware. LongCat-2.5 gives you a managed, always-updated API with no infrastructure to run. Teams with GPUs, privacy requirements, or huge volume often favour the open model; teams that want zero ops and the latest capabilities favour the closed one. Capability is close enough that this operational question, not the benchmark, usually decides it.
Want both DeepSeek V4.1 Flash and LongCat-2.5 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
See pricingFrequently asked questions
Is DeepSeek V4.1 Flash or LongCat-2.5 better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, DeepSeek V4.1 Flash leans toward software engineering (deepswe v1.1: 74.2, essentially level with claude opus 5's 74.0) while LongCat-2.5 leans toward native multimodal upgrade to longcat-2.0 - 1.6t total parameters, about 48b active per token, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, DeepSeek V4.1 Flash or LongCat-2.5?
DeepSeek V4.1 Flash is open-weight, so self-hosting means no per-token fee (you pay for hardware instead), while LongCat-2.5 is API-metered at $0.3/$1.2 per 1M tokens. For most teams without GPUs, the API model is cheaper to start; at very high volume, self-hosting can win.
Which has the bigger context window?
Effectively neither — 1.05M tokens vs 1M tokens is a difference of a few percent. Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both DeepSeek V4.1 Flash and LongCat-2.5 together?
Yes — a multi-model platform like LumiChats gives you DeepSeek V4.1 Flash, LongCat-2.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, DeepSeek V4.1 Flash or LongCat-2.5?
LongCat-2.5 — released November 2, 2026, about 53 days after DeepSeek V4.1 Flash.
Related comparisons
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.