Which is cheaper, GLM-5.3 and GLM-5.3-Flash?

GLM-5.3-Flash has the lowest input price. Per 1M input tokens: GLM-5.3 from $0.56 and GLM-5.3-Flash from $0.07.

Which has the larger context window, GLM-5.3 and GLM-5.3-Flash?

GLM-5.3-Flash has the largest context window: GLM-5.3 1,048,576 tokens and GLM-5.3-Flash 1,310,720 tokens.

Which is better for coding, GLM-5.3 and GLM-5.3-Flash?

GLM-5.3 scores highest on the Artificial Analysis Coding Index: GLM-5.3 74.8 and GLM-5.3-Flash 71.5.

Can I switch between GLM-5.3 and GLM-5.3-Flash without changing my code?

Yes. All of them are served through FastRouter's OpenAI-compatible API, so switching is a change of the model parameter (z-ai/glm-5.3, z-ai/glm-5.3-flash).

GLM-5.3 vs GLM-5.3-Flash

Side-by-side pricing per provider, context window, benchmark scores and speed, all on one OpenAI-compatible API.

GLM-5.3 Z.aiz-ai/glm-5.3

GLM-5.3-Flash Z.aiz-ai/glm-5.3-flash

Creator

Z.ai

Released

Aug 18, 2026

Aug 26, 2026

Context window

1.05M

1.31M

Max output

131K

Input / 1MLowest provider price

$0.56$0.56–$1.40 across 5

$0.07$0.07–$0.15 across 5

Output / 1MLowest provider price

$2.50$2.50–$4.40 across 5

$0.25$0.25–$0.50 across 5

Providers

IntelligenceArtificial Analysis index

44.8

41.8

CodingArtificial Analysis index

74.8

71.5

Accepts

Text

Text, Image, Video

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

GLM-5.3 vs GLM-5.3-Flash: summary

GLM-5.3 and GLM-5.3-Flash are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

GLM-5.3, from Z.ai, has a 1,048,576-token context window, costs from $0.56/1M input and $2.50/1M output tokens across 5 providers and scores 44.8 on the Artificial Analysis Intelligence Index.

GLM-5.3-Flash, from Z.ai, has a 1,310,720-token context window, costs from $0.07/1M input and $0.25/1M output tokens across 5 providers and scores 41.8 on the Artificial Analysis Intelligence Index.

GLM-5.3-Flash is the cheapest on input, 8× cheaper than the next model, GLM-5.3-Flash has the largest context window, GLM-5.3 scores highest for intelligence and GLM-5.3 leads on coding.

Switch with one line

client = OpenAI(base_url="https://api.fastrouter.ai/api/v1", api_key="<FASTROUTER_API_KEY>") client.chat.completions.create(model="z-ai/glm-5.3", messages=[...]) # or client.chat.completions.create(model="z-ai/glm-5.3-flash", messages=[...])

Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis