Developer tools
Two utilities for the files developers handle: a JSON formatter that runs entirely in your browser, and a generator that drafts SKILL.md files for Claude. They handle your text differently, and each page says exactly how.
All developer tools
Why a formatter should run locally
The JSON you want to read is rarely public. It is a webhook payload with a signing secret in it, a config export with database credentials, a log line containing an email address. Most online formatters post that text to a server to pretty-print it, and their privacy policies are the only thing standing between your paste and their logs. The JSON Formatter here parses with your browser’s own JSON.parse, so the text never leaves the page. You can watch the network tab stay empty while you work.
Formatting and validating are the same operation: the parser either accepts the text and reformats it, or rejects it and reports where. The tool turns the engine’s message into a line and column, which is usually all you need. For the cases a parser can’t catch (duplicate keys, integers too large to survive a round trip), read Why is my JSON invalid?.
Drafting skills for Claude
A skill is a folder with a SKILL.md file that teaches Claude a repeatable task: frontmatter with a name and a description, then Markdown instructions. Writing one well takes a model, so the SKILL.md Generator is the one tool on this site that does not run in your browser. The description you type is sent to Anthropic’s API through our server, the draft comes back, and this site keeps none of it. The page says so before you press the button, and the draft is checked against the published format and left editable, because it is a draft.
That difference is the rule for this shelf. A tool that can do its job in the browser does, and tells you so. A tool that needs an outside service says which one, what it sends, and what is kept. If there is a developer task you keep reaching for a random website to do, tell us. The PDF to Text extractor under PDF tools is the other utility developers tend to want.
Developer guides
All guides →- Why Is My JSON Invalid?A parser rejected your JSON and handed you something like “Expected double-quoted property name at position 7”. That names the place, not the cause. Here is what it is almost always telling you.
- How to Create a Claude SkillA Claude skill is a folder holding a SKILL.md file that teaches Claude a task you keep repeating. To create a Claude skill you need no code: a folder, a short file with two required fields, and a test. This guide covers the five steps, with the rules from the published format, and points to the deeper guides where a step needs one.
- How to Write a SKILL.md FileWriting a SKILL.md file is mostly a writing problem, not a formatting one. The format is two required fields and some Markdown. What decides whether Claude uses the skill is the description, and what decides whether the result is any good is how the instructions are written. This guide covers both, using the rules in Anthropic's authoring guide and the Agent Skills specification.
- Claude SKILL.md Format ExplainedThe SKILL.md format has two parts: YAML frontmatter that tells Claude when to use the skill, and a Markdown body that tells it how. Two fields are required, four more are in the open specification, and Claude Code understands a further set that no other surface accepts. This page lists every field with its limits, as published in the Agent Skills specification and Anthropic's documentation.
- How to Build a Claude Code SkillA Claude Code skill is a SKILL.md file in a folder that Claude Code watches. That much is shared with every other surface. What is specific to Claude Code is where it looks, how a skill becomes a slash command with arguments, and the frontmatter that controls who can invoke it and which tools it may use without asking. This guide covers those parts, as documented in the Claude Code skills reference.
- Claude Skills vs MCPClaude Skills and MCP get compared because both extend what Claude can do, but they extend different things. A skill changes what Claude knows: it is a folder of instructions loaded when a task matches. MCP, the Model Context Protocol, changes what Claude can reach: it is an open standard for connecting to outside tools and data through servers. Most real setups use both, and this guide explains where the line falls.
- How to Install a Claude SkillInstalling a Claude skill means putting a folder where the product you use looks for it. There are three products with three different answers, and skills do not sync between them. This guide gives the exact location for each, what to check before installing a skill someone else wrote, and why a skill sometimes fails to appear.
- How to Structure a SKILL.md FileThe structure of a SKILL.md file follows one idea: Claude should load as little as possible until it needs more. The specification calls this progressive disclosure, and it shapes everything from the order of sections to which files sit next to SKILL.md in the folder. This guide gives a section order that works, the folder layout, and the rules for splitting a skill that has grown.
- SKILL.md Examples and TemplatesThe fastest way to understand the SKILL.md format is to read a few finished files. These five SKILL.md examples are complete, pass the format checks, and use only the six frontmatter fields in the Agent Skills specification, so each works in Claude Code, claude.ai, and the API. Copy the one nearest your task and change the specifics.