Seq Documentation and Support

Welcome to the Seq documentation hub. You'll find comprehensive guides and documentation to help you start working with Seq as quickly as possible, as well as support if you get stuck. Let's jump right in!

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Seq works best with richly-structured event data like that produced by Serilog, ASP.NET Core and NLog 4.5+.

If you currently use log4net however, you're not left out; we provide a log4net appender that writes events to Seq via HTTP.

Installing the Appender

At the time of writing, the Seq appender for log4net supports .NET 4+.


Logging performance and latency

For adequate logging performance, we recommend the use of Log4Net.Async, and show its configuration in the example below.

At the Visual Studio Package Manager console, type:

PM> Install-Package Seq.Client.Log4Net
PM> Install-Package Log4Net.Async

This will add the required assemblies to the project.

Then, add the Seq appender to your log4net configuration. This is wrapped in a Log4Net.Async AsyncForwardingAppender so that the application does not pause while log events are flushed to Seq:

<?xml version="1.0" encoding="utf-8" ?>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
    <appender name="SeqAppender" type="Seq.Client.Log4Net.SeqAppender, Seq.Client.Log4Net" >
      <serverUrl value="http://localhost:5341" />
      <apiKey value="" />
    <appender name="SeqAsyncForwarder" type="Log4Net.Async.AsyncForwardingAppender,Log4Net.Async">
      <appender-ref ref="SeqAppender" />
      <level value="INFO" />
      <appender-ref ref="SeqAsyncForwarder" />

Set the serverUrl value under to the address of your Seq server.

Writing events

That's it! When you write log events to your log4net ILogger:

log.InfoFormat("Hello, {0}, from log4net!", Environment.UserName);

They'll appear beautifully in Seq.

Updated 10 months ago


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