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Span-01 Lite

Also accepted:respan/span-01-lite:free
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Span-01 Lite is a behavior-scoring classifier from Respan — the free, lighter tier of Span-01, a 4B model trained with RLAIF on classification reasoning rather than fixed taxonomies. Send a conversation span and a set of plain-language behavior definitions and get a present / absent / not_observable probability per behavior in a single forward pass, with no token-by-token generation. Respan reports it ahead of Jev 1.13 and Sonnet 5 on their English and multilingual behavior-detection suites. Call POST /api/v1/decisions (POST /api/v1/systemone is the same handler).

Providers
Capabilities
OpenRouter
openrouter-byok
$0
$0
Unavailable
Decisions try-it
Run a typed decision request and inspect its structured answers.
Full app

Noul

noul

Does this email need a reply?

A binary answer with probability.

Example result

Yes · 99%

Showing Noul example

AnyRouter support email

Prioritize a support email, classify the request, and grade launch impact.

POST /api/v1/decisions
Edit state, then run the typed questions.
427 / 12,000 characters

Plain text, email, JSON, logs, or a concise state summary.

Typed questions

3 questions

requires_replynoul
Does this email require a human response from AnyRouter support?
request_typechoice
What is the primary request in this email?
business_impactscore
How much business impact does this request have?
Checking session…
respan/span-01-lite
Structured fields or the actual JSON payload.

Structured answers appear here

Run the request to see typed probabilities and fields.

Usage analytics

Loading usage…

API & code

Decisions API

/api/v1/decisions

Typed decisions (noul, choice, score).

Uptime & Health
No uptime data yet

These providers haven't been health-probed for this model yet. The router still routes around upstreams that fail live requests — uptime fills in once probe history accrues.

Share cards
Span-01 Lite share card
Span-01 Lite
OpenRouter upstream share card
OpenRouter upstream
Credits
Use your own key

Run Span-01 Lite on your own key — your requests are billed by the provider. Pool callers pay AnyRouter credits.

No BYOK keys configured for this model yet.

Share a key with the pool to earn credits for every request it serves, covering your plan cost.

Decisions
Context length0 tokens
ArchitectureTransformer
Categorytext
ReleasedSep 26, 2026
Modalities
Capabilities
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