blazor

A guide for building interactive web interfaces with C# through Microsoft's Blazor framework, instead of writing most interface code in JavaScript. It covers server-rendered, browser-run, and hybrid rendering options.

In plain words
What is it for?
Use it when building Blazor applications, choosing a render mode, managing component state, handling prerendering, or connecting C# components to JavaScript.
Why use it?
It helps developers choose how the interface runs and avoid common problems with component structure, shared state, page loading, and browser-server communication.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/managedcode/dotnet-skills/blazor
Any agent
npx skills add managedcode/dotnet-skills --skill blazor
Clone the repo
git clone --depth 1 https://github.com/managedcode/dotnet-skills

Made for: Claude Code, Codex.

Per session 119 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,869 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00119 $0.01869
Opus 5 $0.00060 $0.00934
Sonnet 5 $0.00024 $0.00374
Haiku 4.5 $0.00012 $0.00187

Measured yesterday against content hash 6ea36ef1f5db, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

blazor scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

catalog/Frameworks/Blazor/skills/blazor/SKILL.md · 251 lines

How it starts

The opening of the file, as written. The whole thing — 251 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Blazor

Trigger On

  • building interactive web UIs with C# instead of JavaScript
  • choosing between Server, WebAssembly, or Auto render modes
  • designing component hierarchies and state management
  • handling prerendering and hydration
  • integrating with JavaScript when necessary

Documentation

References

  • patterns.md - Detailed component patterns, state management strategies, and JS interop techniques
  • anti-patterns.md - Common Blazor mistakes and how to avoid them

Render Modes (.NET 8+)

Mode Where It Runs Best For
Static Server (no interactivity) SEO pages, marketing content
InteractiveServer Server via SignalR Real-time apps, thin clients
InteractiveWebAssembly Browser via WASM Offline-capable, client-heavy
InteractiveAuto Server first, then WASM Best of both worlds

Applying Render Modes

@* Per-component *@
@rendermode InteractiveServer

@* Or in App.razor for global *@
<Routes @rendermode="InteractiveAuto" />

InteractiveAuto Architecture

First Request:
  Browser → Server (Interactive Server) → Fast response

Subsequent Requests:
  Browser → WASM (downloaded in background) → No server needed

Workflow

  1. Choose render mode based on requirements:
    • Need SEO? Start with Static or prerendering
    • Need real-time? Use InteractiveServer
    • Need offline? Use InteractiveWebAssembly
    • Want both? Use InteractiveAuto

Read the full file on GitHub · 251 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 251 lines · 119 tokens per session scan A 6ea36ef1f5db

Subscribe to this mod's changes

blazor is a skill published in the GitHub repository managedcode/dotnet-skills (477 stars, last pushed 2d ago), licensed MIT. It adds 119 tokens to every session and 1,869 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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