Which is cheaper, Claude Fable 5.1 and GLM-5.3?

GLM-5.3 has the lowest input price. Per 1M input tokens: Claude Fable 5.1 from $10.00 and GLM-5.3 from $0.56.

Which has the larger context window, Claude Fable 5.1 and GLM-5.3?

GLM-5.3 has the largest context window: Claude Fable 5.1 1,000,000 tokens and GLM-5.3 1,048,576 tokens.

Which is better for coding, Claude Fable 5.1 and GLM-5.3?

Claude Fable 5.1 scores highest on the Artificial Analysis Coding Index: Claude Fable 5.1 79.1 and GLM-5.3 74.8.

Can I switch between Claude Fable 5.1 and GLM-5.3 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 (anthropic/claude-fable-5.1, z-ai/glm-5.3).

Claude Fable 5.1 vs GLM-5.3

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

Claude Fable 5.1 Anthropicanthropic/claude-fable-5.1

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

Creator

Anthropic

Z.ai

Released

Sep 1, 2026

Aug 18, 2026

Context window

1.05M

Max output

128K

131K

Input / 1MLowest provider price

$10.00

$0.56$0.56–$1.40 across 5

Output / 1MLowest provider price

$50.00

$2.50$2.50–$4.40 across 5

Providers

IntelligenceArtificial Analysis index

51.2

44.8

CodingArtificial Analysis index

79.1

74.8

Accepts

Text, Image, Files

Text

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Claude Fable 5.1 vs GLM-5.3: summary

Claude Fable 5.1 and GLM-5.3 are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Claude Fable 5.1, from Anthropic, has a 1,000,000-token context window, costs $10.00/1M input and $50.00/1M output tokens and scores 51.2 on the Artificial Analysis Intelligence Index.

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 is the cheapest on input, 18× cheaper than the next model, GLM-5.3 has the largest context window, Claude Fable 5.1 scores highest for intelligence and Claude Fable 5.1 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="anthropic/claude-fable-5.1", messages=[...]) # or client.chat.completions.create(model="z-ai/glm-5.3", messages=[...])

Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis