UMA optimistic oracle
Optimistic oracle that verifies any statement with bonds, a challenge period and token-holder votes.
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UMA key facts
| Category | Blockchain oracle |
|---|---|
| Chains | Ethereum and EVM networks |
| Platforms | Web |
| Token | UMA |
| Open source | Yes, AGPL-3.0 on GitHub (UMAprotocol/protocol) |
| Security audits | OpenZeppelin audits since April 2020, latest March 2, 2026; bug bounty |
| US availability | Available: terms restrict only sanctioned jurisdictions |
| Fees | Requesters pay the reward they set; asserters lock a bond of at least the finalFee, returned if undisputed |
UMA token
- Price
- $0.3104 -1.2% 24h
- Market cap
- $28.5M
- Fully diluted value
- $40.9M
- 30-day change
- -25.6%
Market data: CoinGecko, updated Nov 10, 2026. Educational content, not financial advice.
What is UMA?
UMA runs the Optimistic Oracle, which verifies statements rather than streaming prices. A claim is posted with a bond, stands if no one disputes it during a challenge period, and goes to a UMA token-holder vote if disputed. Polymarket and Across use it, per UMA's homepage.
How UMA works
A request to UMA's Optimistic Oracle states how it should resolve, a proposer reward, the bond a proposer must post and a challenge window.
A proposer answers once and posts the bond. If nobody disputes within the window, two hours by default, the answer settles and the proposer gets the reward and the bond back. In OOV3 a disputer who proves a proposal wrong receives half of the proposer bond, and the rest goes to UMA's Store contract. UMA says 99.8% of requests settle without escalation.
Disputes go to the DVM on Ethereum mainnet. UMA stakers commit secret votes for 24 hours and reveal them over the next 24 hours, and a result needs at least 65% of staked UMA behind one outcome. Stakers who skip a vote or vote with the minority are slashed, and the slashed UMA goes to the majority. On chains without a native bridge to Ethereum, a multisig controlled by Risk Labs engineers relays disputes and results.
How to start with UMA
- Integrators choose Optimistic Oracle v2, v3 or ManagedOptimisticOracleV2 and set the bond and liveness for each request.
- UMA says the main reason to raise the bond or the challenge window is security for complex requests or ones that could move large sums.
- Proposing on ManagedOptimisticOracleV2 uses a whitelist: 5 or more Polymarket or Predict.fun proposals and over 95% accuracy in the last 6 months, refreshed monthly.
- Voters stake UMA in the voter dapp, and unstaking takes one week.
UMA fees and limits
- Approval, staking, unstaking and reward claims are not rebated, and since June 15, 2026 delegates of voting pools no longer qualify.
On OOV2 the minimum bond equals the final fee listed for each approved collateral token, and on OOV3 you query getMinimumBond(token). Voters pay Ethereum gas to commit and reveal, and Risk Labs rebates it in ETH each month for voters with at least 1,000 UMA staked, covering the full base fee.
Risks to know before using UMA
- UMA's network page lists two setups that Risk Labs monitors: Across on Ethereum mainnet and Polymarket and Predict.fun on Polygon.
- Requests from unmonitored integrations may be misconfigured so that a proposer's bond is stuck permanently, and Risk Labs does not reimburse those losses.
- OpenZeppelin has audited UMA contracts many times, most recently the Dispute Router module and Across diff on March 2, 2026, and UMA runs a bug bounty.
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Where UMA ranks on DappAtlas
UMA pros and cons
- Handles arbitrary questions, not only prices
- Used by Polymarket and Across
- Code public on GitHub under AGPL-3.0
- Answers arrive only after the challenge period, so it does not fit live price feeds
- Disputed outcomes depend on UMA token-holder votes
UMA FAQ
What is UMA?
UMA runs the Optimistic Oracle, which verifies statements rather than streaming prices. A claim is posted with a bond, stands if no one disputes it during a challenge period, and goes to a UMA token-holder vote if disputed. Polymarket and Across use it, per UMA's homepage.
Which chains does UMA support?
Ethereum and EVM networks.
How much does UMA cost?
Requesters pay the reward they set; asserters lock a bond of at least the finalFee, returned if undisputed, according to UMA’s own page (checked Oct 1, 2026).
Does UMA have a token?
Yes, UMA. Its market cap was $28.5M on CoinGecko on Nov 10, 2026. Educational content, not financial advice.
Is UMA available in the US?
Available: terms restrict only sanctioned jurisdictions, according to UMA’s own page (checked Sep 26, 2026).
Sources
- UMA: official site
- UMA: Home
- UMA: GitHub repository
- UMA Docs: Audit and bug bounty programs
- UMA: Terms of Service
- UMA: Docs, Optimistic Arbitrator
- UMA Docs: How does UMA work
- UMA Docs: Setting custom bond and liveness parameters
- UMA Docs: Default proposer whitelist
- UMA Docs: Voting gas rebates
- UMA Docs: Network information
- CoinGecko
How this page works
Sources: UMA: official site, UMA: Home, UMA: GitHub repository. Data as of Oct 1, 2026.
Not affiliated with any project listed. Educational content, not financial advice.