Which is cheaper, GPT-5.4 and GLM-5.3-Flash?

GLM-5.3-Flash has the lowest input price. Per 1M input tokens: GPT-5.4 from $2.50 and GLM-5.3-Flash from $0.07.

Which has the larger context window, GPT-5.4 and GLM-5.3-Flash?

GLM-5.3-Flash has the largest context window: GPT-5.4 1,050,000 tokens and GLM-5.3-Flash 1,310,720 tokens.

Which is better for coding, GPT-5.4 and GLM-5.3-Flash?

GLM-5.3-Flash scores highest on the Artificial Analysis Coding Index: GPT-5.4 71.1 and GLM-5.3-Flash 71.5.

Can I switch between GPT-5.4 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 (openai/gpt-5.4, z-ai/glm-5.3-flash).

GPT-5.4 vs GLM-5.3-Flash

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

GPT-5.4 OpenAIopenai/gpt-5.4

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

Creator

OpenAI

Z.ai

Released

Mar 5, 2026

Aug 26, 2026

Context window

1.05M

1.31M

Max output

128K

131K

Input / 1MLowest provider price

$2.50$2.50–$2.75 across 2

$0.07$0.07–$0.15 across 5

Output / 1MLowest provider price

$15.00$15.00–$16.50 across 2

$0.25$0.25–$0.50 across 5

Providers

IntelligenceArtificial Analysis index

39.0

41.8

CodingArtificial Analysis index

71.1

71.5

LatencyMedian time to first token

19s

—

ThroughputMedian tokens per second

<1 t/s

—

Accepts

Text, Image, Files

Text, Image, Video

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

GPT-5.4 vs GLM-5.3-Flash: summary

GPT-5.4 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.

GPT-5.4, from OpenAI, has a 1,050,000-token context window, costs from $2.50/1M input and $15.00/1M output tokens across 2 providers and scores 39.0 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, 36× cheaper than the next model, GLM-5.3-Flash has the largest context window, GLM-5.3-Flash scores highest for intelligence and GLM-5.3-Flash 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="openai/gpt-5.4", 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