SHARED FORMAT
What carries over
The state + questions structure and question types noul/choice/score match the published Jev schema; probability answers follow the same documented shape for single-question requests.
Jev alternatives · comparison
A Jev-compatible decision API on open models
System1 Models accepts the documented Jev request shape — state plus typed questions — matching TypeSafe’s published OpenAPI schema, checked 28 September 2026. Migration is not drop-in: the launch differences below apply. Jev is a trademark of TypeSafe AI and System1 Models is not affiliated with TypeSafe.
Start free
Sign in with Google, create an API key and send text decisions right away; new accounts get 100M free input tokens. Top-ups: Germany today; EU businesses and more countries soon. Image input is coming soon. Launch rates are listed on the pricing page.
At a glance
System1 Models vs the published Jev list
Dated, sourced figures — last checked 27 September 2026.
| System1 Models | TypeSafe Jev (published list) | |
|---|---|---|
| Input tokens | $0.025–$0.040 / 1M, by model and tier | $0.042 / 1M list price |
| Output tokens | Free — decisions return no generated prose | Free per published list |
| Request format | state + one typed question (noul, choice, score) per request | state + typed questions |
| Models | Open-weight decision models (Plumb-4B, Winnow-12B Q8) | Proprietary Jev model family |
| EU processing | EU tier: contracted EU operators only, inference in Finland; DPA at signup | See TypeSafe documentation |
| Benchmark evidence | Compare model implementations across five equally presented sources, including weaker results and missing coverage. See the full benchmark matrix and method → | |
| Access | Sign in with Google, 100M free input tokens — get an API key | TypeSafe account signup |
Sources: TypeSafe Jev list price, checked 27 Sep 2026; Five-source matrix, methods and conflict disclosure; checked 30 September 2026; approved System1 launch rates.
The format
Keep questions structured
At launch, each request carries a state and exactly one named question of type choice, yes/no or score. Answers include a selected value and, where supported, probabilities.
Request shape
{"state":"Mia owns a red bicycle.","questions":{"color":{"type":"choice","instructions":"Which color is the bicycle?","criteria":{"red":null,"blue":null}}}}Comparison
What changes when you migrate?
The shared request shape matches TypeSafe’s published OpenAPI request and answer schema for the documented decision types (checked 28 September 2026); the surrounding service contract is System1-specific.
SEPARATE SERVICE
What differs
One question per request at launch; score rubrics need at least two levels (the published Jev schema also accepts one). System1 model IDs, bearer keys, the S1-Region tier header, idempotency behavior, billing and limits. Byte-for-byte compatibility is not claimed beyond the documented request shape.
Jev and TypeSafe are trademarks of TypeSafe AI. System1 Models is not affiliated with TypeSafe AI, does not resell Jev, and references the marks only to describe compatibility (nominative use). Read the full migration notes →