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Chainlink Users FAQ

The target audience for this FAQ is consumers of Chainlink data - in other words, those looking to integrate Chainlink in order to write real-world data into their blockchain smart contract.

The following is a list of frequently-asked questions and answers collected from our experience supporting the #nodes, #operator-requests, and #external-adapters channels within the Chainlink Official Discord server.

On this page:

General Topics​

While market.link was previously the go-to directory for public Chainlink oracle and job listings, this website has since been deprecated, and will soon be migrated to Dune Analytics. In the meantime, there is no centralized directory for Chainlink oracles.

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LinkWell Nodes offers custom Chainlink jobs / data feeds on over 12 testnets and 14 mainnets. To get started making your first request, feel free to visit our Chainlink request documentation.

For those interested in reading more about how to find a Chainlink oracle, we recommend reading our blog post on it.

The blockchain networks that Chainlink supports can be determined by viewing Chainlink's LINK token contracts. Please note that this list is subject to change over time as Chainlink adds or removes support for a given chain.

Please see the following answer in our Node Operator FAQ here.

How do I find a specific price feed?​

Contract addresses for official Chainlink price feeds across the various blockchain networks supported by Chainlink can be found here.

If you can't find a price feed that works for you, we'd be happy to support your request. Please feel free to visit our data feed documentation to get started! You can also shop around for other node operators via the #operator-requests channel of the Chainlink Official Discord server.

Where can I find an Oracle Address and Job ID for my smart contract?​

The best place to request a Job ID specific to your requirements is within the #operator-requests channel of the Chainlink Official Discord server. An existing node operator will typically respond to your request by providing you with a corresponding Job ID and oracle contract address.

If you're looking to get started using LinkWell Nodes as your oracle data provider, please feel free to visit our data feed documentation, which contains job IDs, oracle addresses, and smart contract code samples for initiating your first oracle request against our Chainlink oracle infrastructure.

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Have a question? Please feel free to join our Discord server for immediate assistance!

What is a Direct Request job?​

Direct Requests - also known as Basic Requests, are the technology underpinning Chainlink's Any API functionality.

Please see our Direct Request knowledgebase article for more information on how direct requests work, and how to get started initiating a request yourself.

My request transaction won't send​

Please ensure that you have enough gas token present in the wallet that is initiating the request. For mainnet requests, please additionally ensure that you have the appropriate amount of LINK tokens present within your consumer contract before making the request.

If you are using one of our jobs, see the setFeeInHundredthsOfLink() function call present within the constructor of your consumer contract for the minimum amount of LINK token that needs to be present within your consumer contract in order to initiate a request() call.

I'm not getting a response back to my consumer contract​

If you've waited over 60 seconds after successfully sending your request transaction, and aren't seeing any data returned to your smart contract:

  1. Double-check that you are passing the correct values into the _setChainlinkToken() and _setChainlinkOracle() functions , and assigning the correct value to the jobId object.
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If you are using our oracle services, you may find the correct corresponding values in our job documentation here.

  1. Confirm that the API endpoint to which you are making your HTTP request is working via curl.
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If you are using our oracle services, a sample curl command is included within the documentation for each job here.

  1. If you've included a JSON path var (ie, req._add("path", "key1,0,key2)), ensure that the response returned by your HTTP request is in JSON format, and that the provided path exists within it.

  2. If you've included a mulitiplier var (ie, req._addInt('multiplier', 10 ** 18)), ensure that the response that you are trying to multiply is a number. If a JSON path was also included in the request, the multiplication operation occurs on the result of the JSON path filter.

  3. Confirm that the oracle you are using didn't run out of gas while writing your requested data on-chain. To check this, look up the address of your related oracle (ie, the address passed to your _setChainlinkOracle() function) within the appropriate blockchain explorer, to check for any recent transactions that failed due to an 'out of gas' error. If so, you'll need to either A) Return a smaller response, B) Split your request into multiple oracle transactions, or C) Contact the corresponding oracle team to request a higher gas allowance for your specific use case (may result in higher job pricing).

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If you are using our oracle services, you may find the oracle address that corresponds to your specific job within our job documentation here, or reach out to us regarding higher gas limits for your specific use case via our Discord server.

Currently, Chainlink Functions is in beta, and available only to whitelisted participants on a subset of mainnets. You can apply for access here.

While Chainlink Functions is superior to the traditional Direct Request model in many aspects (ie, your request logic is executed by a trustless DON / Decentralized Oracle Network, instead of by a single Chainlink Oracle team), it's important to consider the many tradeoffs in making your decision.

To determine whether Chainlink Functions is right for you, we've included a couple of resources below which should assist you in making your decision:

Despite the many advantages of using Chainlink Functions, there are several limitations that need to be considered before determining whether it is the right fit for your use case.

You should use Chainlink Functions only if ALL of the following apply:

  • You are OK with your logic being executed multiple times per request (ie, this might not be ideal for placing a trade, or sending an email)
  • Your ERC-20 address has been whitelisted by Chainlink Labs for access to Chainlink Functions (may take up to 2 weeks in some cases)
  • You don't need a mainnet deployment ASAP (Functions is currently in mainnet beta)
  • Your use case is limited to the following supported networks
  • You are comfortable programming your request in JavaScript
  • Your consumer contract's callback function will always require less than 300,000 gas (ie, a short string).
  • Your JavaScript code can execute in under 5 minutes
  • Your JavaScript code requires less than 128 megabytes of memory to run
  • The request sent by your JavaScript code is under 30kb
  • Your response you expect from Chainlink is under 256 bytes
  • Your JavaScript code makes at most 5 HTTP requests, each of which respond within 3 seconds
  • Your HTTP requests don't return a payload of more than 2 megabytes (ie, a large image file)

To read more Chainlink Functions, including its benefits and limitations, you may view the official Chainlink documentation here:

Chainlink Functions are better than external adapters in many ways - namely, enabling you to maintain your own deployment lifecycle (ie, no contact with node operators), while being able to run your job against a decentralized network of oracle operators for a low fee. To learn more about the advantages of using Chainlink Functions, read our write-up about it here.

There are however, some use cases where using an external adapter does make sense - namely, if you're using a network that's not yet supported on Functions, you already have an external adapter developed and don't want to re-write it using JavaScript, or if you'd like your logic developed for you by a node operator. You can read more about the limitations of using Chainlink Functions here.

External Adapters​

If you already have an external adapter, you can choose to either connect it to your own Chainlink node, or reach out to an existing Chainlink node operator, who will typically host your adapter on their redundant infrastructure for free.

To help you decide whether to run your Chainlink node, read our write-up about it here.

Are external adapters decentralized?​

This depends on your app's requirements around decentralization and trust-minimization. Typically, just a single node operator hosts your adapter and returns your data to your application. Although a typical node operator will host your adapter on highly-redundant infrastructure, this may represent single point-of-failure (SPOF) for your application, as well as require a certain level of trust between you and the node operator.

In choosing where to host your external adapter, you may also choose to reach out to a DON (Decentralized Operator Network) - an aggregation network comprised of multiple node operators - to host your adapter. This represents a trust-minimized approach, wherein your adapter is hosted by multiple oracle teams, and aggregation is done at the protocol level before being returned to your contract.

To get connected with the appropriate oracle operator(s) for your external adapter's use case, we suggest reaching out within the #operator-requests channel of the Chainlink Official Discord server.

Security​

Can I use a single data source for my data feed?​

While using a single data source can be a sufficient approach for testnet applications, it represents a single point-of-failure (SPOF) for your application, and thus is typically not recommended for mainnet / production applications.

To keep your Web3 application decentralized, we recommend requesting your data from multiple data sources, and performing some sort of aggregation (mean, median, mode, etc.) within your job / external adapter / function logic in order to determine the appropriate result.

At LinkWell Nodes, we are certainly happy to help you set up a job that aggregates your decentralized production data. Please feel free to join our Discord server to get started!

Can I trust a single node operator?​

Any time you make a request for data to a singular node, that node could possibly manipulate the data (ie, if they were a malicious actor). However, it's likely that any kind of profitable data manipulation by a singular node operator would quickly be identified, and the reputation of the node operator destroyed.

At LinkWell Nodes, our reputation - and our customers' happiness - is the key to our business model, and to our continued success. Leveraging our team's vast experience in the financial services, government, and Web3 industries, we ensure that our infrastructure is SOC-2 compliant, and meets or exceeds the same security standards used by your bank. In addition, we monitor all aspects of our infrastructure using world-class, enterprise-grade monitoring tools.

Please reference our Service-Level Agreement (SLA) for more information about our uptime and security guarantees.

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For those in need of maximum decentralization, you might consider using a DON (Decentralized Oracle Network). As community-based node operators, the only type of DON for which we are able to provide support are the legacy Flux Monitor networks, which are highly expensive to the consumer, as the fees and support complexities typically scale directly with the number of node operators supporting the DON. The benefit of our data feed offerings, however, is their relatively quick implementation time (time-to-market), and our ability to immediately provide support and resolution without involving other node operators.

Do you have any security guarantees?​

For information about our security and service guarantees, please visit our Service-Level Agreement (SLA).