42. Top 10 blockchain oracles. How do they work? How do they differ?

Blockchain technology is powerful. It allows us to build decentralized apps, execute smart contracts without middlemen, and create transparent financial systems. But even the most advanced blockchains have a major limitation — they can’t access real-world data on their own.

That’s where blockchain oracles come in. These tools are the bridge between blockchain systems and the outside world, helping smart contracts make decisions based on real-life events.

What Are Blockchain Oracles?

Imagine a smart contract that needs to release funds when a flight is delayed, or when ETH hits a certain price. The blockchain itself doesn’t know if the flight was late or what the current ETH price is.

Blockchain oracles solve this problem. They feed off-chain data — like prices, weather updates, GPS locations, or sports results — into blockchain applications. Without oracles, smart contracts would be stuck in their own isolated world.

With oracles, they can:

• trigger automatic payments,

• adjust values in DeFi apps,

• settle bets in prediction markets,

• track assets in supply chains,

• and much more.

Where Do Oracles Get Their Data?

Oracles gather data from various sources, depending on what’s needed:

• APIs from exchanges like Binance or Coinbase,

• IoT devices, like temperature sensors or QR scanners,

• Human input, for example from experts like meteorologists,

• Or aggregated feeds from multiple sources to boost reliability.

Most oracles rely on multiple nodes (computers) to verify the data before it’s sent to the blockchain. This reduces the chance of errors or manipulation.

Types of Oracles

Not all oracles work the same way. Here are the main types:

• Inbound oracles – send information into the blockchain (like price feeds).

• Outbound oracles – send blockchain data out to the real world (like triggering a bank payment).

• Hardware oracles – gather data from physical devices.

• Software oracles – get information from web-based sources.

• Decentralized oracles – use multiple nodes to verify data, avoiding a single point of failure.

• Centralized oracles – rely on one trusted source (faster but riskier).

• Human oracles – real people input data manually.

• Contract-specific oracles – created for a single task and shut down afterward.

Top 10 Blockchain Oracles – Updated as of June 11, 2025

1. Chainlink (LINK)
   Market leader in blockchain oracles, supporting Ethereum, BNB Chain, Avalanche, and more. Offers the Cross-Chain Interoperability Protocol (CCIP) for secure messaging across chains.
   Price: USD 15.35

2. Band Protocol (BAND)
   Cosmos-native oracle using Delegated Proof of Stake (DPoS) to ensure data integrity and resistance to manipulation.
   Price: USD 0.7273

3. UMA (UMA)
   Specializes in synthetic assets and financial smart contracts on Ethereum. Widely used in prediction markets and options.
   Price: USD 1.52

4. DIA (DIA)
   Open-source data aggregator pulling from both centralized and decentralized exchanges, with support for custom data feeds.
   Price: USD 0.4449

5. API3 (API3)
   Provides decentralized APIs (“dAPIs”) with no middlemen. Its flagship Airnode solution makes it easy for APIs to become blockchain-native.
   Price: USD 0.7681

6. XYO Network (XYO)
   Focuses on geospatial data, using a decentralized network of devices to validate locations of users and assets.
   Price: USD 0.01089

7. iExec RLC (RLC)
   Off-chain compute marketplace akin to decentralized cloud services such as AWS.
   Price: USD 1.095

8. Tellor (TRB)
   Ethereum-based oracle where “reporters” stake TRB tokens to submit data—and are rewarded or slashed based on accuracy.
   Price: USD 46.73

9. Nest Protocol (NEST)
   Operates on Ethereum, using a quotation-mining mechanism that incentivizes on-chain price accuracy and transparency.
   Price: USD 0.00015824

10. DOS Network (DOS)
    Layer-2–capable oracle known for high throughput and scalability across multiple chains.
    Price: Unavailable (low liquidity; limited exchange listings)

Why Are Oracles So Important?

Without oracles, smart contracts would be blind. Oracles give them the ability to react to real-world events, enabling:

• DeFi apps to update prices in real time,

• NFT games to sync in-game rewards with off-chain events,

• DAOs to vote based on real-world outcomes,

• and logistics apps to track real items.

In short, oracles unlock the full potential of blockchain technology.