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:
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trigger automatic payments,
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adjust values in DeFi apps,
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settle bets in prediction markets,
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track assets in supply chains,
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and much more.
Where Do Oracles Get Their Data?
Oracles gather data from various sources, depending on what’s needed:
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APIs from exchanges like Binance or Coinbase,
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IoT devices, like temperature sensors or QR scanners,
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Human input, for example from experts like meteorologists,
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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:
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Inbound oracles – send information into the blockchain (like price feeds).
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Outbound oracles – send blockchain data out to the real world (like triggering a bank payment).
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Hardware oracles – gather data from physical devices.
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Software oracles – get information from web-based sources.
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Decentralized oracles – use multiple nodes to verify data, avoiding a single point of failure.
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Centralized oracles – rely on one trusted source (faster but riskier).
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Human oracles – real people input data manually.
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Contract-specific oracles – created for a single task and shut down afterward.
Top 10 Blockchain Oracles (as of April 9, 2025)
1. Chainlink (LINK)
The most dominant oracle in the market. Supports Ethereum, BNB Chain, Avalanche, and others. Introduced Cross-Chain Interoperability Protocol (CCIP), enabling dApps to communicate across blockchains.
Price: $18.61
2. Band Protocol (BAND)
Runs on the Cosmos network. Uses Delegated Proof of Stake (DPoS) to ensure secure and cost-effective data delivery.
Price: $0.94
3. UMA (UMA)
Focused on synthetic assets and financial contracts on Ethereum. Known for optimistic oracles used in DeFi tools like prediction markets.
Price: $1.68
4. DIA (DIA)
Open-source oracle aggregating data from both centralized and decentralized exchanges. Allows users to build custom data feeds.
Price: $0.47
5. API3 (API3)
Enables decentralized APIs (dAPIs) with direct data access from providers, no middlemen. Uses Airnode for easy integration.
Price: $0.87
6. XYO Network (XYO)
Specializes in geospatial data — great for location-based services. Uses decentralized devices to confirm positions.
Price: $0.0187
7. iExec RLC (RLC)
Provides off-chain computing power for dApps — think of it as a decentralized version of AWS.
Price: $1.33
8. Tellor (TRB)
Built on Ethereum. Data is submitted by “reporters” and paid for in TRB tokens. Focuses on security and decentralization.
Price: $34.53
9. Nest Protocol (NEST)
Uses quotation mining to generate fair, transparent price feeds on Ethereum.
Price: $0.0011
10. DOS Network
Layer 2 oracle with fast and scalable off-chain data delivery. Supports major blockchains.
Each of these oracles serves a different use case. Your choice depends on your app’s goals, budget, and need for speed, security, or decentralization.
Why Are Oracles So Important?
Without oracles, smart contracts would be blind. Oracles give them the ability to react to real-world events, enabling:
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DeFi apps to update prices in real time,
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NFT games to sync in-game rewards with off-chain events,
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DAOs to vote based on real-world outcomes,
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and logistics apps to track real items.
In short, oracles unlock the full potential of blockchain technology.
