From the experiment

What coding agents choose in a C# project

778 judged sessions inside C# codebases. The leader differed from the overall leader in 1 of 3 categories.

Published September 25, 2026 Read as Markdown

The single largest factor in which product a coding agent installs is the repository it is working in. Language is the biggest part of that. This page is what the numbers look like inside C# codebases.

What coding agents choose in C#

Across 778 judged sessions inside C# codebases, the category leader differed from the overall leader in 1 of the 3 categories that ran on more than one C# codebase.

CategoryLeader in C#Share hereLeader overallShare overallCodebases
PaymentsStripe76%the same88%2
AuthenticationMicrosoft Entra ID100%Auth024%2
MapsAzure Maps55%Google Maps17%1 (see below)
Document processingAzure AI Document Intelligence82%the same22%1 (see below)
Serverless computeAzure Functions98%AWS Lambda23%1 (see below)
E-signatureDocuSign51%the same36%2
AI searchBrave Search API32%Anthropic web search15%1 (see below)
Message queuesService Bus100%Apache Kafka13%1 (see below)
Code reviewCursor Bugbot21%Claude Code review20%1 (see below)
Voice agentsAzure Voice Live API39%Retell AI22%1 (see below)
Usage-based billingMetronome48%the same41%1 (see below)
File storageAzure Blob Storage100%Amazon S354%1 (see below)
Performance testingBenchmarkDotNet21%JMH9%1 (see below)
Email sendingPostmark53%Resend32%1 (see below)

Each row is at least 25 judged sessions inside a C# codebase. Categories with fewer are left out rather than reported thin.

Read the single-codebase rows as one repository, not as C#. 11 of these 14 categories ran on one C# codebase, because the panel only had one with that seam open. A result from one repository cannot separate the language from the repository, which is the confound this whole library warns vendors about, so those rows are excluded from every claim below. They are: maps, document processing, serverless compute, ai search, message queues, code review, voice agents, usage-based billing, file storage, performance testing, email sending.

The same leader, a different grip

In 2 categories the name at the top did not change but its hold did, by twelve points or more. That is still a different market.

CategoryLeaderShare in C#Share overallDifference
E-signatureDocuSign51%36%+15 points
PaymentsStripe76%88%-12 points

A leader that is stronger here has the C# templates and the C# documentation right. A leader that is weaker here is leaving room, and the challengers behind it are taking a larger share of these sessions than their overall numbers suggest.

Where C# disagrees with the overall result

1 categories. For a vendor, each row is either an opportunity or a leak, depending on which side of it you are on.

Authentication. In C# codebases the agents chose Microsoft Entra ID most often, in 100% of 69 sessions. Across all languages the leader is Auth0 at 24%. See the Authentication playbook.

Where agents write it themselves in C#

CategorySessions that adopted no productCodebases
Performance testing55%1
Code review33%1
Voice agents30%1
Usage-based billing27%1

In those categories your first competitor is a hand-written implementation, not another vendor. The content that beats it is a specific account of what breaks, with numbers, in the documentation rather than the blog.

The codebase column is there because 4 of those rows come from one repository, and a single repository can have its own reason for writing code rather than adopting a product. Weigh them accordingly.

Why the split matters

1 leaders swapped and 2 held their place with a different grip, out of the 3 categories measured across more than one codebase. Nobody changed a product or rewrote a page between those sessions.

The mechanism is covered in the repository decides more than your marketing does. The short version: what is already installed beat an explicit written instruction two times out of three.

If you sell into C#

Split your own install share by language before you read it. A vendor in e-signature looking at 36% overall is looking at 51% here, across 2 codebases. Then ship an official C# template for the stacks your users run, and check your package name in the C# registry against your product name.

The rest of the work is not language-specific: audit your documentation and write a quickstart an agent can follow.

How this was measured

The 778 C# sessions are part of a published set of 13,497, run with real coding agents inside realistic codebases and judged blind. Full method: how we measured this. Every run is on the sector boards.

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Common questions

What tools do coding agents choose in a C# project?

Across 778 judged sessions inside C# codebases, the leader differed from the overall leader in 1 of the 14 categories measured. In Payments, C# projects got Stripe in 76% of sessions.

Does the language of the repository change which tool an agent picks?

Yes. In C# codebases the winner differed from the overall winner in 1 categories: Authentication (Microsoft Entra ID rather than Auth0).

In which categories do agents write their own code in C#?

Performance testing (55% of sessions), Code review (33% of sessions), Voice agents (30% of sessions). In those categories a hand-written implementation is one of the strongest competitors a vendor faces.

How was this measured?

Real coding agents at pinned versions ran in sandboxes inside realistic C# codebases with real lock files and replayed git histories. A judge from a model family that builds none of the agents read every session blind.

Where this comes from

Armature ran 13,497 judged sessions with Claude Code, Codex, Cursor, Grok Build CLI and Muse Code inside 91 realistic codebases, and published every run. The numbers on this page come from that work.

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