Antimatter

POST/v1/ensembleAPI key

Every member is priced at its worst case before anything is sent, and the sum is held to max_cost_micros, the key's per request ceiling, the monthly cap and what the account can spend. Each member then runs as its own keyed chat completion (no presets, aliases or fallback), with its own request id, hold and usage row under the ensemble's id as session, and spends one request of the key's per minute window. The combined answer is computed: a vote, a field by field JSON vote, or the cheapest answer that passes a check; only the judge rule asks a model, the one the caller names, billed as one more member. A failed member does not fail the ensemble; all of them failing is a 502 ensemble_failed. stream is refused: the combined answer exists only at the end. On a deployment with $ANTI holder tiers the ensemble is for holders: a key whose minting account does not hold the lowest tier is refused with 403 holder_only.

Request body

application/json, required

Request body fields
Field	Type	What it is
members	array of string or object	The models, as ids or autopilot ids, each optionally with its own max_tokens and temperature. Give these or preset. An autopilot id is routed before anything is priced, inside the key's allowlist and blocklist.
preset	string	A member list by name: tiers is antimatter/auto:cheap, antimatter/auto, antimatter/auto:quality. Two tiers that land on one model run it once. One of "tiers".
combine	object	The rule: majority (match, min_agreement), json-consensus (needs a JSON response_format), first-valid (the JSON check, pattern, or both) or judge (judge_model, which you name and pay for). majority when absent.
combine.rulerequired	string	One of "majority", "json-consensus", "first-valid", "judge".
combine.match	string	One of "normalized", "exact".
combine.min_agreement	number	From 0 to 1.
combine.pattern	string	At most 1000 characters.
combine.judge_model	string	At most 200 characters.
max_cost_micros	integer	Refuse the ensemble, sending nothing, when the worst case of every member and the judge together is over this, in micro dollars. At most 9007199254740991.
member_timeout_ms	integer	How long one member may run, 120000 ms when absent. A member past it is reported as timed out; one aborted after it reached the upstream is billed. From 1000 to 240000.
messagesrequired	array of any	The conversation every member answers. The rest of the body is a chat request every member shares; stream, model and models are refused.

Example

{
  "messages": []
}

Answer 200

Every member's answer, cost and latency, and the combined answer.

Headers: x-antimatter-request-id, x-request-id, x-antimatter-cost-micros, x-ratelimit-limit, x-ratelimit-remaining, x-ratelimit-reset

Fields of the 200 answer
Field	Type	What it is
id	string	ens_ and the request id's digits; every member's usage row carries it as its session.
object	"ensemble"
created	integer
rule	string	One of "majority", "json-consensus", "first-valid", "judge".
combined	object	The combined answer. ok false with a reason when no answer qualified (every answer failed the check, the plurality was under min_agreement, the judge named no candidate); the members are still there, and still billed.
combined.ok	boolean
combined.content	string or null
combined.member	integer or null	Whose answer it is; null for a field by field JSON merge.
combined.agreement	number	The share of answering members behind it.
combined.chosen_by	string	One of "computed", "model_judgment".
combined.method	string	One of "field-wise", "whole".
combined.votes	array of object
combined.checks	array of object
combined.fields	array of object
combined.tie_broken_by_price	boolean
combined.note	string
combined.reason	string
members	array of object
members[].index	integer
members[].requested	string	The id as given, autopilot ids included.
members[].model	string	The model that answered and was billed.
members[].status	integer
members[].ok	boolean
members[].content	string or null
members[].tool_calls	array of object
members[].finish_reason	string or null
members[].usage	object or null
members[].cost_micros	integer	What this member was billed.
members[].worst_case_micros	integer	What it was priced at before sending.
members[].latency_ms	integer
members[].request_id	string	Its own request id: GET /v1/requests/{id}.
members[].timed_out	boolean
members[].error	object
members[].error.type	string
members[].error.message	string
judge	object
judge.index	integer
judge.requested	string	The id as given, autopilot ids included.
judge.model	string	The model that answered and was billed.
judge.status	integer
judge.ok	boolean
judge.content	string or null
judge.tool_calls	array of object
judge.finish_reason	string or null
judge.usage	object or null
judge.cost_micros	integer	What this member was billed.
judge.worst_case_micros	integer	What it was priced at before sending.
judge.latency_ms	integer
judge.request_id	string	Its own request id: GET /v1/requests/{id}.
judge.timed_out	boolean
judge.error	object
judge.error.type	string
judge.error.message	string
usage	object	Every member's tokens summed, and cost in dollars.
cost_micros	integer
worst_case_micros	integer
max_cost_micros	integer

Errors

400OpenAI shaped error.
401OpenAI shaped error.
402OpenAI shaped error.
403OpenAI shaped error.
404OpenAI shaped error.
413OpenAI shaped error.
429Rate limited, or a spent budget or spend cap. The type distinguishes rate_limit_error, policy_exceeded, and spend_cap_exceeded.
502OpenAI shaped error.
503OpenAI shaped error.

Every error answers in one shape, with its type, code and the field it names. The whole list is in the docs' Errors section.

Try it

The same call with curl

curl -X POST https://useantimatter.com/v1/ensemble \
  -H "Authorization: Bearer $ANTIMATTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"messages":[]}'