GLM-5.1 vs GPT-5.3-Codex
GLM-5.1 (2026) and GPT-5.3-Codex (2026) compare a standalone API model against a coding-specialized model. GLM-5.1 ships a 200k-token context window, while GPT-5.3-Codex ships a 400k-token context window. On SWE-bench Pro, GLM-5.1 leads by 1.6 pts. On pricing, GLM-5.1 costs $1.05/1M input tokens versus $1.75/1M for the alternative. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: GLM-5.1 is standalone API model, while GPT-5.3-Codex is coding-specialized model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | GLM-5.1 | GPT-5.3-Codex |
|---|---|---|
| Product type | Standalone API model | Coding-specialized model |
| Best for | reasoning-heavy apps, tool-calling agents, and provider-routed production | custom coding agents, code generation, and tool loops |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 200k | 400k |
| Cheapest output | $3.50/1M tokens | $14/1M tokens |
| Provider routes | 5 tracked | 3 tracked |
| Shared benchmarks | SWE-bench Pro leader | 3 shared |
Decision tradeoffs
- GLM-5.1 holds a shared-benchmark lead on SWE-bench Pro, ahead by 1.6 points.
- GLM-5.1 has the lower cheapest tracked output price at $3.50/1M tokens.
- GLM-5.1 has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags GLM-5.1 for Coding, RAG, and Agents.
- GPT-5.3-Codex holds a shared-benchmark lead on Terminal-Bench 2.0, ahead by 13.8 points.
- GPT-5.3-Codex has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.3-Codex uniquely exposes Vision and Computer use in local model data.
- Local decision data tags GPT-5.3-Codex for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
GLM-5.1
$1,715
Cheapest tracked route/tier: OpenRouter
GPT-5.3-Codex
$4,900
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $3,185. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.3-Codex is $10.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GPT-5.3-Codex adds Vision and Computer use in local capability data.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- GLM-5.1 is $10.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision and Computer use before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-07 | 2026-02-05 |
| Context window | 200k | 400k |
| Parameters | 754B total, 40B active | — |
| Architecture | Mixture of Experts | Decoder Only |
| License | MITOSI-approved | Proprietary |
| Openness | Open source | Proprietary |
| Weights | Available | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: permitted | Commercial use: conditional |
| Knowledge cutoff | 2025-11 | 2025-08 |
Pricing and availability
| Pricing attribute | GLM-5.1 | GPT-5.3-Codex |
|---|---|---|
| Input price | $1.05/1M tokens | $1.75/1M tokens |
| Output price | $3.50/1M tokens | $14/1M tokens |
| Providers |
Capabilities
| Capability | GLM-5.1 | GPT-5.3-Codex |
|---|---|---|
| Vision | No | Yes |
| Multimodal | No | No |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | Yes |
| Parallel agents | No | No |
Benchmarks
| Benchmark | GLM-5.1 | GPT-5.3-Codex |
|---|---|---|
| SWE-bench Pro | 58.4 | 56.8 |
| Terminal-Bench 2.0 | 63.5 | 77.3 |
| SWE-rebench | 62.7 | 58.2 |
Continue comparing
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Last reviewed: 2026-06-30. Data sourced from public model cards and provider documentation.