Coding · Head-to-head

GPT-5.5 vs GLM-5.3

GPT-5.5 vs GLM-5.3: pricing, features, and which to pick in 2026.

GPT-5.5View full review →

GLM-5.3View full review →

The verdict

Pick GPT-5.5 if…

→overall capability matters more than price (AI Score 9.4 vs 8.5)
→your primary use case is developers and teams needing a frontier reasoning model for agentic coding workflows and large-codebase context handling.
→you need: development, agents

Try GPT-5.5 →

Pick GLM-5.3 if…

→budget is the constraint

Try GLM-5.3 →

Side-by-side specs

Spec	GPT-5.5	GLM-5.3
Category	Coding	Coding
Pricing model	paid	freemium
Headline pricing	API: $5/$30 per 1M tokens (in/out). ChatGPT Plus $20/mo, Pro $200/mo	Freemium via Z.ai GLM Coding Plan and ZCode (paid tiers for API access)
Free tier	No free API tier. Free ChatGPT users get GPT-4o, not GPT-5.5.	Limited API access and hosted inference
AI Score	9.4/10	8.5/10
Best for	Developers and teams needing a frontier reasoning model for agentic coding workflows and large-codebase context handling.	—
Editor's pick	✓ Yes	✓ Yes
Use cases	development agents	—
Date added	2026-05-02	2026-08-17

Pros and cons

GPT-5.5

Coding · paid

Pros

✓Top-of-class coding and reasoning benchmarks — measurably ahead of GPT-5 and competitive alternatives
✓True agentic capability with tool use, self-correction, and multi-step task completion
✓272K context handles entire codebases without chunking workarounds
✓Codex integration turns it into an autonomous software engineer inside ChatGPT

Cons

×API pricing is premium — $30/M output tokens adds up fast for heavy usage
×No free tier for the API; ChatGPT Free users are stuck on GPT-4o
×Slower inference than lighter models like GPT-4o-mini for simple tasks
×Closed-source with no self-hosting option — full vendor lock-in to OpenAI

GLM-5.3

Coding · freemium

Pros

✓Open weights enable local and fine-tuned deployment
✓Documented 50% coding benchmark lift over GLM-5.2
✓Demonstrated real-world vulnerability discovery
✓Strong long-horizon task performance

Cons

×Requires self-hosting or paid API for full capability
×Newer model with limited third-party ecosystem
×Cybersecurity focus may introduce unintended behaviors in non-security tasks

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Updated 2026-08-17. Spec data sourced from official product pages and tracked in our public directory at /tools.