# Respan: span-01

> Respan's behaviour-scoring model for evals, guardrails and monitoring. For each plain-language behaviour you define, it reads a conversation or agent trace and returns the probability the behaviour is present, absent or not observable, in one forward pass.

- Page: https://systemonemodels.tech/respan/span-01
- API: https://api.systemonemodels.tech/v1/models/respan/span-01

## Facts

| | |
|---|---|
| Maker | Respan (https://systemonemodels.tech/respan) |
| Decides | noul, classify |
| Architecture | span |
| Licence | proprietary |
| Availability | Hosted API |
| Released | 2026-09-24 |
| Latest version | 2026.09 |

## Hosted API

- Provider: Respan (https://respan.ai/docs/documentation/span-01/concept)

- Input: $0.020/MTok · Output: Free

## Model card

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# Span-01

Respan's behaviour-scoring model for evals, guardrails and monitoring. For each plain-language behaviour you define, it reads a conversation or agent trace and returns the probability the behaviour is present, absent or not observable, in one forward pass.

One question type only, served on Respan's own POST /api/v1/scores rather than the /v1/systemone schema. Respan reports an overall F1 of 0.843 on its behaviour benchmark, against 0.715 for Jev 1.13.0 and 0.761 for Span-01 Lite. Span-01 costs $0.02 per million input tokens with output free; Span-01 Lite is free up to a daily cap. Also listed on OpenRouter (respan/span-01). Architecture and size are not published.

## What it decides

- **noul** — answers a yes/no question with one calibrated probability
- **classify** — assigns a category from a fixed taxonomy

## At a glance

| | |
|---|---|
| Maker | Respan |
| Released | 2026-09-24 |
| License | proprietary |

## Hosted API

Served by **Respan** — $0.02/MTok input, $0/MTok output. [Get access](https://respan.ai/docs/documentation/span-01/concept).

## Read more

- [Launch post](https://www.respan.ai/blog/behavior-detection-model-comparison)
- [Docs](https://respan.ai/docs/documentation/span-01/concept)

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*This page was opened by System One for Respan, who can claim the organisation and take it over at any time.*

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From System One Models — https://systemonemodels.tech/ · every System One model: https://systemonemodels.tech/system-one-models