I needed up-to-date .NET mapper benchmarks. They didn't exist.

The day AutoMapper stopped being a no-brainer

For years, AutoMapper was the default. You added the NuGet package, wrote a profile, and never thought about it again. That changed for me in 2025.

Two things happened almost back to back:

1. 
   AutoMapper went commercial. On July 2, 2025, Jimmy Bogard announced commercial editions of AutoMapper (and MediatR) under a new company, Lucky Penny Software. It's still free for individuals and companies under $5M USD in annual revenue, but above that you now need a paid license. ( (CVSS 7.5, High) is a Denial-of-Service via uncontrolled recursion: map a deeply nested object graph and you get a StackOverflowException that takes the whole process down, and in modern .NET you can't even catch it. The catch? The fix landed in the paid versions (15.1.1 / 16.1.1).

So if you're on the free track, you're sitting on a known DoS with no free upgrade path. At work, that meant one thing: we had to migrate AutoMapper out of every project.

The problem: nobody had fresh numbers

There's no shortage of candidates: Mapperly, Mapster, TinyMapper, AgileMapper, or just writing the mapping by hand. The hard part wasn't finding options, it was figuring out which one to actually trust in production, and that's a call you want to make with data, not vibes.

I went looking for benchmarks and hit a wall:

• Most comparisons were years old.


• None were run against .NET 10.


• Library versions were stale, so the conclusions no longer applied.


• Everyone benchmarked slightly different scenarios, so you couldn't compare apples to apples.

Performance characteristics change with every runtime and every library release. A benchmark from 2021 tells you almost nothing about Mapperly 4 on .NET 10. I didn't want a snapshot. I wanted something that stays true over time.

So I built it.

The solution: benchmarks that never go stale

I built a

Open it, pick the scenario that matches your workload, and read today's results instead of mine from whenever you happen to read this.

Try it / steal it

• 
  Live benchmarks:
  


• 
  The website: · GHSA-rvv3-g6hj-g44x / CVE-2026-32933
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