glm 5.3 flashx deepseek v4.1 flash is a pairing problem, not a naming problem. GLM-5.3-FlashX is a high-speed serving tier of Z.ai's GLM-5.3-Flash. DeepSeek-V4.1-Flash is a different model family with its own weights, a larger maximum output, and peak/off-peak prices. Older pages that compare GLM 5.3 Flash with DeepSeek V4 Flash are a different matchup. This one uses the FlashX model code on one side and V4.1-Flash on the other.
Facts below come from the Z.ai Flash/FlashX overview, the Z.ai pricing table, DeepSeek's API pricing page, and DeepSeek's V4.1-Flash announcement, all checked October 12, 2026. We did not run a shared benchmark harness, so this article does not declare a quality winner. "Which wins" here means which bill, limit, and deployment shape fits the job.
Decide before the spec sheet
Pick GLM-5.3-FlashX when you already want Z.ai's Flash behavior and you are paying for the hosted fast tier (glm-5.3-flashx), 128K output is enough, and you do not need a separate FlashX checkpoint.
Pick DeepSeek-V4.1-Flash when off-peak or cache-hit price matters, you need up to 384K output, or you want the exact model weights DeepSeek published. The API name to call is deepseek-flash. DeepSeek still accepts the legacy name deepseek-v4-flash, and those requests are served by V4.1-Flash at Flash prices.
Standard GLM 5.3 Flash versus the previous DeepSeek V4 Flash is a different matchup. FlashX is the hosted speed tier of GLM-5.3-Flash, with its own model code and a higher list price.
Specs that are actually comparable
| GLM-5.3-FlashX | DeepSeek-V4.1-Flash | |
|---|---|---|
| What it is | High-speed variant of GLM-5.3-Flash | Smallest model in DeepSeek's newer architecture family |
| API model id | glm-5.3-flashx | deepseek-flash |
| Scale | 320B total, 18B active (Flash architecture on the Z.ai overview) | 552B backbone; 8B active on input, 16B active on output |
| Context | 1M | 1M |
| Max output | 128K | 384K |
| Input price | $0.37 / 1M; cached input $0.075 / 1M | Peak cache miss $0.30 / 1M; peak cache hit $0.006 / 1M. Off-peak is half |
| Output price | $1.25 / 1M | Peak $1.20 / 1M; off-peak $0.60 / 1M |
| Vision | Images, video, and files in; text out (Z.ai overview) | Native visual understanding; vision is marked supported on the pricing table |
| Published weights | No separate FlashX repo. Weights published for GLM-5.3-Flash | deepseek-ai/DeepSeek-V4.1-Flash |
| Speed | Vendor states 200 tokens/s | Announcement says faster inference and higher throughput. No tokens/s figure is copied here |
The 200 tokens/s line is Z.ai's claim on the overview. We are not repeating an independent median for FlashX in this comparison. DeepSeek's announcement describes a smaller KV cache than its previous Flash generation (about 1/4 the HBM and 1/8 the SSD storage) and does not give a tokens-per-second number we can put next to 200.
Price, including the off-peak trap
List price at peak is close on a cache-miss prompt. For 1M input tokens with a cache miss plus 100K output tokens:
- FlashX: $0.37 + $0.125 = $0.495
- V4.1-Flash peak: $0.30 + $0.12 = $0.42
- V4.1-Flash off-peak: $0.15 + $0.06 = $0.21
Off-peak on DeepSeek's pricing page is 50% of peak, and the V4.1 announcement says the new rates took effect at 04:00 UTC on September 10, 2026. A workload you can shift off-peak is the clearest V4.1 win on the invoice. Cache hits widen it further: DeepSeek's peak cache-hit input is $0.006 per 1M tokens, against $0.075 cached input on FlashX. Do not mix those with GLM Coding Plan points. The Z.ai overview still says FlashX is not on that plan.
Use the table in this section for V4.1, because DeepSeek says retired deepseek-v4-flash names now route to V4.1-Flash and bill at Flash rates. Older V4 Flash price pages describe the retired model, not this alias.
Where the architectures are not the same job
FlashX inherits GLM-5.3-Flash: a hybrid sparse-and-linear attention MoE, 320B total and 18B active, on the Z.ai overview. V4.1-Flash is a Causal Encoder-Decoder MoE. Prefill activates 8B parameters and decode activates 16B, on a 552B backbone, per the announcement. Same "Flash" label, different active-parameter story.
Both official pages support tools and structured output. Both claim a 1M context. The output cap is not the same: 128K on the Z.ai Flash/FlashX page, 384K maximum on DeepSeek's pricing table. Long agent traces that need a single huge completion lean V4.1 before they lean FlashX.
Quality claims stay vendor-scoped. Z.ai publishes GLM-5.3-Flash benchmark figures on its own harnesses. DeepSeek publishes V4.1-Flash results on its own harnesses, including different scaffolds for different benchmarks. Those numbers are not a head-to-head. This article will not average them into a winner.
Local weights change the decision
If "run it myself" is a requirement, V4.1-Flash has a model repository: DeepSeek-V4.1-Flash on Hugging Face. FlashX does not have a matching checkpoint. The weights Z.ai published are GLM-5.3-Flash. Downloading those does not turn your GPUs into the hosted FlashX tier. Local Flash weights and hosted glm-5.3-flashx are different products.
FAQ
Is GLM 5.3 FlashX the same comparison as GLM 5.3 Flash vs DeepSeek V4 Flash?
No. FlashX is the faster serving tier and a higher list price. V4.1-Flash replaced the retired V4 Flash API names. Use this page for that pair, and the older comparison only for standard Flash versus V4 Flash.
Which is cheaper?
On a peak cache-miss prompt, V4.1-Flash's list rates are slightly lower in the example above. Off-peak, V4.1-Flash is about half of its own peak price. FlashX has no off-peak column on the Z.ai table we checked.
Which is faster?
Z.ai states 200 tokens/s for FlashX. DeepSeek describes higher throughput and a much smaller KV cache than its previous Flash, without a tokens/s number we can line up against 200. We did not measure either model for this article.
Can I call the old deepseek-v4-flash name?
Yes, as a legacy alias. DeepSeek's pricing page says deepseek-v4-flash and deepseek-v4-flash-vision-exp are still accepted, the old models are retired, and those requests are served by DeepSeek-V4.1-Flash at the Flash price.
If you want GLM 5.3 Flash itself in a browser, open glm5.app. That site's documented model id is glm-5.3-flash, not the FlashX tier in this comparison.
Sources
- GLM-5.3-Flash/FlashX overview — model code, 1M context, 128K output, 200 tokens/s claim, and the Flash architecture summary. Checked October 12, 2026.
- Z.ai pricing — FlashX list rates used in the worked example.
- DeepSeek models and pricing —
deepseek-flashas V4.1-Flash, 1M context, 384K max output, peak and off-peak rates, legacy name routing. - DeepSeek-V4.1-Flash announcement — 552B backbone, 8B/16B active split, KV-cache comparison, and the September 10, 2026 price effective time.
- DeepSeek-V4.1-Flash weights — published checkpoint for the DeepSeek side of a local-deployment requirement.
