GLM-5.3 hits the API at $1.4/$4.4 per million tokens

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 $0.26 per million tokens, while Z.ai currently lists cached-input storage as free for a limited time. That means developers can move to the new generation without taking a higher posted per-token rate from Z.ai, even as the company claims substantially stronger coding and long-horizon agent performance. At those rates, GLM-5.3 sits well below several of the highest-end frontier APIs. ModelInput ($/1M)Output ($/1M)Total ($/1M)SourceMuse Spark 1.2 Contributor$0.10$0.20$0.30MetaMiMo-V2.5 Flash$0.10$0.30$0.40XiaomiDeepSeek-V4-Flash — off-peak$0.22$0.66$0.88DeepSeekGPT-5.6 Luna$0.20$1.20$1.40OpenAIMiniMax-M3$0.30$1.20$1.50MiniMaxLongCat-2.0 — limited-time promo$0.30$1.20$1.50LongCatDeepSeek-V4-Flash — peak hours$0.44$1.32$1.76DeepSeekMiMo-V2.5$0.40$2.00$2.40XiaomiDeepSeek-V4-Pro — off-peak$0.66$1.98$2.64DeepSeekLongCat-2.0 — standard$0.75$2.95$3.70LongCatMiMo-V2.5 Pro (≤256K)$1.00$3.00$4.00XiaomiGemini 3.6 Flash — through Dec. 31, 2026$0.75$3.75$4.50GoogleGemini 3.7 Flash — through Dec. 31, 2026$0.75$3.75$4.50GoogleDeepSeek-V4-Pro — peak hours$1.32$3.96$5.28DeepSeekMuse Spark 1.1 / 1.2$1.25$4.25$5.50MetaGLM-5.3$1.40$4.40$5.80Z.AIGrok 4.6 — <200K prompt tokens$2.00$6.00$8.00xAIMiMo-V2.5 Pro (>256K)$2.00$6.00$8.00XiaomiQwen3.8-Max$2.00$6.00$8.00QwenCloudGemini 3.6 Flash — starting Jan. 1, 2027$1.50$7.50$9.00GoogleGemini 3.7 Flash — starting Jan. 1, 2027$1.50$7.50$9.00GoogleGPT-5.6 Terra$2.00$12.00$14.00OpenAIGrok 4.6 — ≥200K prompt tokens$4.00$12.00$16.00xAIGPT-5.4$2.50$15.00$17.50OpenAIKimi K3$3.00$15.00$18.00Moonshot AIClaude Opus 5$5.00$25.00$30.00AnthropicSakana Fugu Ultra (≤272K)$5.00$30.00$35.00Sakana AIGPT-5.6 Sol — Standard mode$5.00$30.00$35.00OpenAIClaude Fable 5 / Claude Mythos 5$10.00$50.00$60.00AnthropicGPT-5.6 Sol — Fast mode$10.00$60.00$70.00OpenAIUsing 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. Its 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.