GLM-5.3 vs Seed 2.1 Pro: Specs & Benchmark Comparison
GLM-5.3 is developed by Zhipu AI, while Seed 2.1 Pro comes from ByteDance. Seed 2.1 Pro was released in June 2026, and GLM-5.3 followed 2 months later in August 2026. GLM-5.3 has a published size of about 753 billion parameters; ByteDance has not disclosed the parameter count of Seed 2.1 Pro.
The two models share 8 published benchmarks. GLM-5.3 leads on 6 of them, Seed 2.1 Pro on 2. The widest gaps are on Program Bench, where Seed 2.1 Pro scores 50.3% against 19.0%; PostTrainBench, where GLM-5.3 scores 39.8% against 16.5%. Averaged across everything we track, GLM-5.3 sits at 52.2% and Seed 2.1 Pro at 63.7%.
GLM-5.3 is available through an API at $1.40 per million input tokens with a 1M-token context window. We do not track a hosted API for Seed 2.1 Pro, so pricing and context cannot be compared directly.
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| Characteristic | GLM-5.3 | Seed 2.1 Pro |
|---|---|---|
| Company | Zhipu AI | ByteDance |
| Release Date | August 14, 2026 | June 24, 2026 |
| Parameters | 753B | — |
| Multimodal | No | Yes |
| Context (input) | 1.0M | — |
| Context (output) | 131K | — |
| Input Price / 1M | $1.40 | — |
| Output Price / 1M | $4.40 | — |
| Average Score | 52.2% | 63.7% |
| Benchmarks | ||
| Program Bench | 19.0% | 50.3% |
| PostTrainBench | 39.8% | 16.5% |
| Toolathlon | 73.0% | 50.6% |
| Terminal-Bench 2.1 | 88.0% | 71.0% |
| CyberGym | 84.5% | 70.2% |
| Agents' Last Exam | 28.5% | 41.4% |
| NL2Repo | 58.0% | 47.0% |
| Humanity's Last Exam | 62.5% | 55.7% |
Visual Benchmark Comparison
Verdict
GLM-5.3 leads in 1 out of 2 comparison categories.
Both models show comparable average scores: GLM-5.3 — 0.5, Seed 2.1 Pro — 0.6.
GLM-5.3 is newer: released 8/14/2026 vs 6/24/2026.
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Frequently Asked Questions
Which is better for coding — GLM-5.3 or Seed 2.1 Pro?
Which model is cheaper — GLM-5.3 or Seed 2.1 Pro?
Which has a larger context window — GLM-5.3 or Seed 2.1 Pro?
The GLM-5.3 and Seed 2.1 Pro comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the GLM-5.3 or Seed 2.1 Pro page. See also the complete list of AI model comparisons.