NewsBlogWhat Is an Oracle in Blockchain?

What Is an Oracle in Blockchain?


Algorand Foundation

Revolutionary technologies like blockchain oracles are reshaping how we interact with decentralized systems. This article explores the definition of a blockchain oracle, the types of oracles, and how they can be used in real-world situations. It also explores the "oracle problem" and possible solutions.

What is a blockchain oracle?

A blockchain oracle serves as a bridge between the blockchain and the outside world since a blockchain cannot access off-chain data (information beyond its network) by itself. An oracle allows smart contracts, programs that run on a blockchain, to access real-world data, such as sports match results, stock prices, weather conditions, and more. Oracles are an important part of blockchain infrastructure because they greatly enhance the functionalities of smart contracts, enabling applications to cater to a diverse spectrum of industries, making them applicable to a wide range of industries, including logistics, healthcare, supply chain management, and more. 

Example of a blockchain oracle

Imagine a logistics company that wants to automate its supply chain using blockchain technology. The company's smart contracts are responsible for tracking the movement of goods from the manufacturer to the distributor and finally to the retailer. The smart contracts need to access real-time data about the location of the shipments, temperature conditions, and any potential delays.

In this scenario, a blockchain oracle creates a bridge between the blockchain and various external data sources. For instance, the oracle can connect to GPS systems and IoT sensors embedded in the shipment containers. It can fetch real-time location updates, temperature readings, and other relevant data from these sensors and securely deliver it to the smart contracts on the blockchain.

The smart contracts can now use this real-world data to trigger automated actions, such as updating the status of the shipment, calculating estimated delivery times, and issuing alerts in case of unexpected deviations in temperature or route.

By utilizing oracles in this logistics example, the company gains unprecedented visibility and efficiency in its supply chain operations. Smart contracts can now make data-driven decisions based on real-time information, reducing manual intervention and human errors, and improving overall supply chain management.

Real-world use cases for oracles

Decentralized finance (DeFi): DeFi platforms can use blockchain oracles to access real-world data, enabling smart contracts to perform functions such as borrowing, lending, and decentralized prediction markets.

Real estate: Oracles can enable the verification of property ownership, legal contracts, and transaction data. They can also facilitate automatic payments, ensuring that property transactions are executed efficiently and transparently.

Healthcare: Oracles in healthcare can securely access and verify patient data, medical records, and drug supply chain information. This would ensure the privacy and authenticity of medical records while enabling interoperability between various healthcare systems.

Weather and environmental data: Oracles can connect blockchain networks to weather stations and environmental sensors, providing real-time data on weather conditions, air quality, and natural disasters. This data can be valuable for insurance companies, agricultural practices, and disaster response planning.

Insurance: Insurance companies can leverage blockchain oracles to enhance the efficiency, transparency, and trustworthiness of their operations and insurance products. An oracle can supply information like flight delays or weather conditions, so insurance can be automatically paid out when specific events occur.

Sports and betting: Oracles can supply real-time data for accurate sports event outcomes, scores, and player statistics, ensuring fair and transparent sports betting experiences.

What are the different types of oracles?

Software and hardware oracles 

Software oracles connect to external data sources through APIs and web services. They are capable of retrieving and transmitting data from online platforms, databases, and other software systems. Hardware oracles use physical devices, such as IoT sensors and RFID tags, to collect real-world data. They are commonly used in scenarios where data from the physical environment is required.

Inbound and outbound oracles

Inbound oracles fetch external data and bring it into the blockchain. They are commonly used in scenarios like the supply chain example, where real-time data needs to be accessed and processed by the smart contract. Outbound oracles push data from the blockchain to external systems. This is useful when a smart contract needs to trigger actions in the external world based on specific conditions met on the blockchain.

Centralized and decentralized oracles

Centralized oracles rely on a single entity or a centralized authority to provide data to the smart contract. While they may be easier to implement, they introduce a single point of failure and potential data manipulation. The trust in the data provided by centralized oracles would depend on the reputation and reliability of the central authority. Decentralized oracles operate in a trustless manner, leveraging consensus mechanisms and multiple nodes to fetch, verify, and deliver data to the smart contract. By distributing data retrieval and validation across a network of nodes, decentralized oracles enhance security and resilience.

How do oracles work in smart contracts?

When a smart contract requires external data to execute a specific condition, it sends a request to the designated oracle. The oracle then provides the relevant data gathered from an external source, which could be APIs, IoT sensors, or other data providers. After obtaining the data, the oracle securely delivers it to the smart contract on the blockchain.

For example, consider a supply chain smart contract that needs to verify the authenticity of a product by checking its barcode against a centralized database. The smart contract would send a request to the oracle with the barcode as a parameter. The oracle would then access the external database, retrieve the product information, and provide it to the smart contract. Based on the response, the smart contract can execute the necessary actions, such as updating the product's status on the blockchain.

Oracles will often require payment for contracts to access the data, commonly through their own token. This payment ensures the incentive for oracle operators to provide accurate and timely information.

What is the "oracle problem"?

The "oracle problem" in blockchain refers to the challenge of securely accessing and reliably verifying external data, which can result in data manipulation. It is essential that the data be accurate and tamper-resistant so the smart contract can be trusted to carry out its role correctly. Additionally, ensuring the availability of external data is another concern. Any downtime or unavailability of real-time data sources could disrupt the execution of the smart contracts. Mechanisms must be in place to ensure continuous access to the required data and avoid interruptions. 

Decentralized oracle networks are one of the prominent solutions to the oracle problem. They leverage multiple nodes to fetch and verify data, reducing the risk of single points of failure and enhancing security. However, gaining this information in a decentralized manner comes with its own issues. For example, you could ask everyone watching a football match to input the final score, but if the stadium is filled with supporters of the losing team, could they be trusted to submit the accurate result? 

Oracles and Algorand

Goracle is a decentralized oracle network. It enhances the capabilities of DApps in the Algorand ecosystem, allowing them to interact with real-world events and data in a trustless and secure manner.

Tellor is a transparent and permissionless oracle protocol that enhances the Algorand ecosystem by providing reliable off-chain data with cryptographic guarantees. Tellor can be leveraged across multiple blockchain networks.

Further reading 

What Is a DApp? Decentralized Apps Explained

How to Become a Blockchain Developer: A Guide to Getting Started


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