After a stunning debut last week with cyber capabilities so advanced they reportedly found a previously undetected vulnerability in Cursor, GLM-5.3, the new frontier open source language model from Chinese startup z.ai, has now hit the application programming interface (API) — allowing developers the ability to build atop it and plug it into their agents and applications.
Developers who previously subscribed to a GLM Coding Plan are currently limited to the OpenAI Chat Completions-compatible protocol. Z.ai said it plans to make the model's weights openly available, but a precise date and licensing remain to be seen.
On the API, the price is unchanged from GLM-5.2: $1.40 per million input tokens and $4.40 per million output tokens. Cached input costs $0.26 per million tokens, while Z.ai currently lists cached-input storage as free for a limited time.
That means developers can move to the new generation without taking a higher posted per-token rate from Z.ai, even as the company claims substantially stronger coding and long-horizon agent performance.
At those rates, GLM-5.3 sits well below several of the highest-end frontier APIs.
|
Model |
Input ($/1M) |
Output ($/1M) |
Total ($/1M) |
Source |
|
Muse Spark 1.2 Contributor |
$0.10 |
$0.20 |
$0.30 |
|
|
MiMo-V2.5 Flash |
$0.10 |
$0.30 |
$0.40 |
|
|
DeepSeek-V4-Flash — off-peak |
$0.22 |
$0.66 |
$0.88 |
|
|
GPT-5.6 Luna |
$0.20 |
$1.20 |
$1.40 |
|
|
MiniMax-M3 |
$0.30 |
$1.20 |
$1.50 |
|
|
LongCat-2.0 — limited-time promo |
$0.30 |
$1.20 |
$1.50 |
|
|
DeepSeek-V4-Flash — peak hours |
$0.44 |
$1.32 |
$1.76 |
|
|
MiMo-V2.5 |
$0.40 |
$2.00 |
$2.40 |
|
|
DeepSeek-V4-Pro — off-peak |
$0.66 |
$1.98 |
$2.64 |
|
|
LongCat-2.0 — standard |
$0.75 |
$2.95 |
$3.70 |
|
|
MiMo-V2.5 Pro (≤256K) |
$1.00 |
$3.00 |
$4.00 |
|
|
Gemini 3.6 Flash — through Dec. 31, 2026 |
$0.75 |
$3.75 |
$4.50 |
|
|
Gemini 3.7 Flash — through Dec. 31, 2026 |
$0.75 |
$3.75 |
$4.50 |
|
|
DeepSeek-V4-Pro — peak hours |
$1.32 |
$3.96 |
$5.28 |
|
|
Muse Spark 1.1 / 1.2 |
$1.25 |
$4.25 |
$5.50 |
|
|
GLM-5.3 |
$1.40 |
$4.40 |
$5.80 |
|
|
Grok 4.6 — <200K prompt tokens |
$2.00 |
$6.00 |
$8.00 |
|
|
MiMo-V2.5 Pro (>256K) |
$2.00 |
$6.00 |
$8.00 |
|
|
Qwen3.8-Max |
$2.00 |
$6.00 |
$8.00 |
|
|
Gemini 3.6 Flash — starting Jan. 1, 2027 |
$1.50 |
$7.50 |
$9.00 |
|
|
Gemini 3.7 Flash — starting Jan. 1, 2027 |
$1.50 |
$7.50 |
$9.00 |
|
|
GPT-5.6 Terra |
$2.00 |
$12.00 |
$14.00 |
|
|
Grok 4.6 — ≥200K prompt tokens |
$4.00 |
$12.00 |
$16.00 |
|
|
GPT-5.4 |
$2.50 |
$15.00 |
$17.50 |
|
|
Kimi K3 |
$3.00 |
$15.00 |
$18.00 |
|
|
Claude Opus 5 |
$5.00 |
$25.00 |
$30.00 |
|
|
Sakana Fugu Ultra (≤272K) |
$5.00 |
$30.00 |
$35.00 |
|
|
GPT-5.6 Sol — Standard mode |
$5.00 |
$30.00 |
$35.00 |
|
|
Claude Fable 5 / Claude Mythos 5 |
$10.00 |
$50.00 |
$60.00 |
|
|
GPT-5.6 Sol — Fast mode |
$10.00 |
$60.00 |
$70.00 |
Using the simple VentureBeat comparison of one million input tokens plus one million output tokens, GLM-5.3 comes to $5.80, versus $8 for Grok 4.6 at its lower context rate, $18 for Kimi K3, $30 for Claude Opus 5 and $35 for GPT-5.6 Sol.
That is not a workload-cost estimate — real bills depend heavily on the input/output mix, caching and token consumption — but it makes the relative API price tier easy to see.
GLM-5.3 is not the cheapest capable model available. Google’s current introductory price for Gemini 3.7 Flash is $0.75 per million input tokens and $3.75 per million output tokens through Dec. 31, 2026, while OpenAI’s GPT-5.6 Luna is priced at $0.20 input and $1.20 output.
Still, Z.ai’s price puts GLM-5.3 into a notably lower cost band than the premium frontier models it is increasingly benchmarked against.
That comparison has become more relevant following the latest independent results. Artificial Analysis gives GLM-5.3 a score of 60 on its Intelligence Index, tying Kimi K3 as the top performing open weights model in the world, and scoring seven points higher than GLM-5.2. I
ts analysis also estimates GLM-5.3 at about $0.68 per Intelligence Index task, versus roughly $0.44 for GLM-5.2, despite the identical API token prices.
The difference underscores an important caveat in headline API pricing: Artificial Analysis found GLM-5.3 more verbose than its predecessor, so flat per-token rates do not necessarily mean flat costs for a completed workload.
For developers, though, the immediate change is straightforward: GLM-5.3 is now callable through Z.ai’s API at the same $1.40/$4.40 per-million-token rate as GLM-5.2, giving teams another relatively low-cost option for testing frontier-class coding and agent workloads.
