Arena
Arena (formerly LMArena, Chatbot Arena). What it was engaged to test, on what terms, what it found in the document's own words, and what happened afterwards. Every line is a record; every record links to the document it was read from.
- Founded2025
- HQnot stated
- Registry idnone cited (company)
- TestsCrowd-vote model leaderboards; pre-release testing for providers; paid AI Evaluations; Arena Alignment Index (Oct 2026).
- Money, as the roster puts itVenture: $100M seed (May 2025, a16z and UC Investments), $150M Series A (Jan 2026, Felicis and UC Investments), $200M Series B at $3.1B (Oct 2026, Lightspeed and Khosla); customers include model labs, none named.
- Filesdossier · observatory, sliced to it · graph
- Labs tested
- no lab document names it
- Models
- no model named
- Span of engagements
- none dated
- Terms and findings
- 0 of 0 documents state a term · 0 quote a finding
- Money in, US dollars, stated single-recipient rows
- no stated figure 7 in · 0 outfrom Andreessen Horowitz
- Seats, by side
- no seat names it
- Afterwards
- no later event on record
Each count is the number of store records that name this evaluator. An engagement is one lab document naming it for one model; an outcome is an event on the record afterwards; the money, seats and moves are the observatory's rows filtered to it. A cell that cannot be filled says not stated, and each table ends with how many of its rows state each field.
Filters combine: any of the values ticked within a dimension, all of the dimensions at once. A table that has no column for a dimension you have set says so instead of showing rows that cannot match. The address bar carries the slice.
What it was engaged to test 0 engagements
In date order, each from the lab document that names the evaluator. Under each: the four terms that document states (access, model stage, publication, payment) and the finding in its words. A term the document is silent on reads not stated; the tags beside the terms are read off their words and are what the console filters on.
No lab document on record names this evaluator for a model.
Dated 0 of 0Model named 0 of 0Terms stated 0 of 0Finding quoted 0 of 0
The terms, as the documents state them
The same engagements as a grid, one row per document and model, so the silences line up: a document that gives an access window but no payment term, or a finding but no publication term, reads that way here.
| Document | Model | Access window | Model stage | Publication | Payment | Finding | Record |
|---|---|---|---|---|---|---|---|
| no engagement on record | |||||||
Access window 0 of 0Model stage 0 of 0Publication 0 of 0Payment 0 of 0Finding, quoted 0 of 0
What happened afterwards 0 on record
Events a party published after an engagement: an incident on a model this evaluator's engagement covered, a correction or added disclosure, a later finding that cut against an earlier one, a lab's statement that it acted or did not act on the finding, or a move from this evaluator to a lab it graded. A row the source attaches to this evaluator by name is marked named; one that reaches it through the model it tested is marked via the model. The kind is what the record states, not why.
| Kind | Developer | Model | What the record states | When | Source | Id |
|---|---|---|---|---|---|---|
| no later event on record | ||||||
Dated 0 of 0Model named 0 of 0Tied to an engagement 0 of 0Evaluator named by the record 0 of 0
The money on record 7 rows
Rows of the observatory's money table that name this evaluator as recipient (in) or as funder (out), each as the record states it: a grant table line, a contract notice, a Form 990 schedule or the party's own disclosure. A figure quoted in prose is marked and never summed.
| Direction | Funder | Recipient | Amount, as recorded | When | Record | Source | Id |
|---|---|---|---|---|---|---|---|
| in | Andreessen Horowitz | Vals AI; Arena | no amount publishedArena says it "raised funding from a16z and The University of California" | not dated | party's own page | Vals AI; Arena; Arena, seed; Braintrust; Promptfoo; OpenAI; FEC | 7c90a4560f |
| in | Andreessen Horowitz | Arena | figure in prose, not a stated payment$100M seed (27 May 2025)seed | 27 May 2025 | party's own page | Vals AI; Arena; Arena, seed; Braintrust; Promptfoo; OpenAI; FEC | 4386776373 |
| in | Andreessen Horowitz | Vals AI; Arena | figure in prose, not a stated paymentled Braintrust's $36M Series A (8 October 2024)Series A | 8 October 2024 | party's own page | Vals AI; Arena; Arena, seed; Braintrust; Promptfoo; OpenAI; FEC | 98eb887980 |
| in | Andreessen Horowitz | Vals AI; Arena | no amount publisheda participant in Promptfoo's Series A (29 July 2025), since acquired by OpenAI | 29 July 2025 | party's own page | Vals AI; Arena; Arena, seed; Braintrust; Promptfoo; OpenAI; FEC | 6cc58353c7 |
| in | Andreessen Horowitz | Vals AI; Arena | no amount publishedco-led OpenAI's March 2026 round alongside SoftBank | March 2026 | party's own page | Vals AI; Arena; Arena, seed; Braintrust; Promptfoo; OpenAI; FEC | dab4d02d57 |
| in | Andreessen Horowitz | Vals AI; Arena | $100,000,000A16Z Capital Management, Marc Andreessen and Ben Horowitz gave $100,000,000 to the Leading the Future super PAC on two dates (FEC)to the Leading the Future super PAC on two dates (FEC | not dated | party's own page | Vals AI; Arena; Arena, seed; Braintrust; Promptfoo; OpenAI; FEC | 60729df417 |
| in | Andreessen Horowitz | Vals AI; Arena | no amount publishedno stake size published | not dated | party's own page | Vals AI; Arena; Arena, seed; Braintrust; Promptfoo; OpenAI; FEC | 6c7b9d3282 |
Amount stated 1 of 7Dated 4 of 7Purpose stated 3 of 7Funder profiled 7 of 7Recipient on the roster 7 of 7
Seats and moves 0 seats · 0 moves
Seats read off a team page, a governance page, an appointment notice or a filing that name this organization, and the dated moves into or out of it, from the observatory's own tables.
| Person | Side | Seat, as the record states it | Role | Dates | Source | Id |
|---|---|---|---|---|---|---|
| no seat on record names this evaluator | ||||||
Role read 0 of 0Organization read 0 of 0Organization profiled 0 of 0Dated 0 of 0
Moves
| Person | From | To | When | Source | Id | |
|---|---|---|---|---|---|---|
| no move on record names this evaluator | ||||||
From profiled 0 of 0To profiled 0 of 0Person profiled 0 of 0Dated 0 of 0