GLM-5 9B vs GPT-5.5 Pro
GLM-5 9B (2026) and GPT-5.5 Pro (2026) are frontier-tier reasoning models from Zhipu AI and OpenAI. GLM-5 9B ships a 262K-token context window, while GPT-5.5 Pro ships a 1M-token context window. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing. The goal is to make the tradeoff clear before deeper testing.
GPT-5.5 Pro is safer overall; choose GLM-5 9B when provider fit matters.
Specs
| Released | 2026-02-15 | 2026-04-23 |
| Context window | 262K | 1M |
| Parameters | 9 | — |
| Architecture | decoder only | decoder only |
| License | Open Source | Proprietary |
| Knowledge cutoff | - | - |
Pricing and availability
| GLM-5 9B | GPT-5.5 Pro | |
|---|---|---|
| Input price | - | $30/1M tokens |
| Output price | - | $180/1M tokens |
| Providers | - |
Capabilities
| GLM-5 9B | GPT-5.5 Pro | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: GPT-5.5 Pro, multimodal input: GPT-5.5 Pro, structured outputs: GPT-5.5 Pro, and code execution: GPT-5.5 Pro. Both models share reasoning mode, function calling, and tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: GLM-5 9B has no token price sourced yet and GPT-5.5 Pro has $30/1M input tokens. Provider availability is 0 tracked routes versus 1. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose GLM-5 9B when provider fit are central to the workload. Choose GPT-5.5 Pro when coding workflow support, larger context windows, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, GLM-5 9B or GPT-5.5 Pro?
GPT-5.5 Pro supports 1M tokens, while GLM-5 9B supports 262K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is GLM-5 9B or GPT-5.5 Pro open source?
GLM-5 9B is listed under Open Source. GPT-5.5 Pro is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, GLM-5 9B or GPT-5.5 Pro?
GPT-5.5 Pro has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, GLM-5 9B or GPT-5.5 Pro?
GPT-5.5 Pro has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for reasoning mode, GLM-5 9B or GPT-5.5 Pro?
Both GLM-5 9B and GPT-5.5 Pro expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run GLM-5 9B and GPT-5.5 Pro?
GLM-5 9B is available on the tracked providers still being sourced. GPT-5.5 Pro is available on OpenAI API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.