Datalust, the company behind Seq

Seq is the intelligent search, analysis, and alerting server built for modern structured logs and traces.

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News and announcements

Replace Function

Wednesday, 26 March 2025

Seq 2025.1 introduces a Replace function that replaces occurrences of a pattern with a replacement. To replace the word March with the word April:

select Replace('The month is March', 'March', 'April') 
// 'The month is April'

The pattern may be a

System Notifications

Thursday, 13 March 2025

TL;DR: Seq 2025.1 supports connecting system notifications to an output app instance to proactively receive notifications.

The Seq UI displays notifications when system events are detected, such as this notification that authentication is disabled.

The Seq UI displaying a warning that authentication is disabled.

System notifications include important events that may need to be addressed for Seq to

Faster Percentile

Monday, 03 March 2025

TL;DR: Dashboards, alerts and queries that include percentile calculations will run faster and more efficiently with Seq 2025.1, in exchange for a small reduction in accuracy.

A percentile, or quantile, is the value below which a fraction of values occur. For example, if all Australian adult woman were

New from Datalust

On .NET Live - Application logs and diagnostics with Serilog

Nicholas Blumhardt talks application diagnostics with Cecil Phillip in On .NET Live.

.NET Rocks! #1647 - Rust and C# with Ashley Mannix

Ashley Mannix talks with Carl and Richard about the combination of Rust and C# used at Datalust.

C# and Rust: Combining Managed and Unmanaged Code Without Sacrificing Safety, NDC Oslo 2019

Ashley Mannix explores the tools that .NET and Rust give us to design and build safe and robust hybrid applications.

Parsing in C# from First Principles, NDC Sydney 2018

Nicholas Blumhardt talks about Superpower, the library we built for parsing SQL queries in Seq, and the foundational principles behind it.

Open Source and the Future of Seq

Brendan Richards interviews Nicholas Blumhardt about Open Source, Rust, Seq, Serilog, and more, in this AMA from NDC Sydney 2018.

Using Structured Logging for Production Insight

Microsoft's Damian Brady and Nicholas Blumhardt talk structured logging in this episode of The DevOps Lab.

.NET Rocks! #1466 - The Evolution of Serilog

Richard Campbell, Carl Franklin, and Nicholas Blumhardt talk all things logging, diagnostics, and monitoring in this .NET Rocks! episode recorded at NDC Oslo 2017.

Serilog: Instrumentation that Works for You, NDC Oslo 2017

Nicholas Blumhardt presents a complete walk-through of Serilog and modern structured logging at NDC Oslo 2017.