flutter-implement-json-serialization Skill for Claude: What It Does and How to Install It

Makes Claude write Flutter model classes with hand-written fromJson and toJson methods, and parse large JSON in the background.

Installs: 38.3K; on skills.sh
Stars: 3.1K; on GitHub
Updated: Nov 2026; last repo commit

This is the Flutter team's skill for manual JSON handling. Claude writes plain model classes with a fromJson factory and a toJson method, using dart:convert and explicit casts.

It also covers fetching with the http package. Small payloads are parsed directly, and large ones go to a background isolate with compute(). The skill's own description limits it to simple data structures.

Good for

Flutter developers mapping simple API responses to Dart classes
Beginners who want type-safe JSON handling without code generation
Teams fixing UI jank from parsing big JSON lists

Install flutter-implement-json-serialization

Claude Code

Copy this prompt.

Install the flutter-implement-json-serialization skill in Claude Code. Run this command:

npx skills add https://github.com/flutter/agent-plugins --skill flutter-implement-json-serialization

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

From its listing on skills.sh. Source.

What's in the skill

When it loads

Create model classes with `fromJson` and `toJson` methods using `dart:convert`. Use when manually mapping JSON keys to class properties for simple data structures.

Sections in SKILL.md

Contents
Core Guidelines
Workflow: Implementing a Serializable Model
Workflow: Fetching and Parsing JSON
Examples
High-Fidelity Model Implementation
Synchronous Parsing (Small Payload)
Background Parsing (Large Payload)

Key facts

Author: Flutter team
License: BSD-3-Clause
Installs on skills.sh: 38,308 (Nov 2, 2026)
GitHub stars: 3,136 for the whole flutter/agent-plugins repo (Nov 2, 2026)
Last repo commit: Nov 1, 2026
What it includes: 1 file: SKILL.md (no scripts)
Needs: A Flutter project. The fetch example uses the http package
Part of: flutter/agent-plugins, which lists 10 Flutter skills in its README
Works in: Not listed. The README names no supported clients and links to docs.flutter.dev/ai/get-started for setup in your preferred agent

What it includes

Casts jsonDecode results and throws on bad HTTP status
Always cast the dynamic result of jsonDecode to Map<String, dynamic> or List<dynamic>. Throw an exception on a non-success status code instead of returning null.
Read · Core rules
Writes the class, fromJson factory and toJson method
Plain class with final fields, a factory Model.fromJson(Map<String, dynamic>) and a toJson() that returns a Map. Ends with unit tests for both methods.
Try: “Implement JSON serialization for the User model class.”
Write · Serializable model
Uses the http package, then decides how to parse
Checks the status code (200, or 201 for POST), then parses on the main thread for small payloads.
Write · Fetch and parse
Uses compute() for large payloads
For arrays of thousands of objects, or parsing that takes over 16 ms, moves parsing to an isolate to avoid UI jank.
Write · Background parsing

From the official docs

Permissions

Low risk

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

The fetch example calls a network URL
The example uses https://api.example.com as a placeholder. Point it only at an API you trust and review the generated code before you run it. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details

Turning on read-only	No read-only mode. Use version control.
Talks to	HTTP requests from the http package example, to the URL you supply
Sign-in and keys	SKILL.md does not mention any account or key.
Scopes	Writes Dart model classes and unit tests in your project The fetch example uses the http package to call a URL you supply

Questions

What does the flutter-implement-json-serialization skill do?

It tells Claude how to turn JSON into Dart objects by hand. Claude writes fromJson and toJson, casts types safely, and moves large parsing jobs to a background isolate.

How do I install flutter-implement-json-serialization?

Use the install box at the top of this page. The skill is one SKILL.md file, so there is nothing else to download. Start a new session afterwards so it loads.

Does it use json_serializable or code generation?

No. The skill's description says it is for manually mapping JSON keys to class properties on simple data structures with dart:convert.

When does it parse in the background?

When parsing takes longer than 16 ms, for example an array of thousands of objects. Small single objects are parsed on the main thread.

Is it safe?

It writes Dart model classes and unit tests in your project, and its fetch example uses the http package against a URL you supply. Review the generated code and keep the project under version control.

Does flutter-implement-json-serialization work in Codex or Cursor?

The README does not list supported clients. It links to https://docs.flutter.dev/ai/get-started for installing the plugins in your preferred agent, so follow that guide for Codex or Cursor.

Information

updated Nov 2, 2026

Repository: flutter/agent-plugins
Folder: skills/flutter-implement-json-serialization

flutter/agent-plugins skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 2

flutter-implement-json-serialization SKILL.md · github.com
Flutter agent-plugins README · github.com