---
title: "Format code"
description: "Format code in your documentation with syntax highlighting, line numbers, diffs, copy buttons, and interactive code group features in MDX."
keywords: ["code blocks", "syntax highlighting", "code styling"]
---

## Add code samples

You can add inline code snippets or code blocks. Code blocks support meta options for syntax highlighting, titles, line highlighting, icons, and more.

### Inline code

To denote a `word` or `phrase` as code, enclose it in backticks (\`).

```mdx
To denote a `word` or `phrase` as code, enclose it in backticks (`).
```

### Code blocks

Use [fenced code blocks](https://www.markdownguide.org/extended-syntax/#fenced-code-blocks) by enclosing code in three backticks. Code blocks are copyable, and if you have the assistant enabled, users can ask the assistant to explain the code.

Specify the programming language for syntax highlighting and to enable meta options. Add any meta options, like a title or icon, after the language.

<Tip>
  To display several code blocks together as a set of tabs (as the examples on this page do), wrap them in the [`CodeGroup`](/components/code-groups) component. Each code block's title becomes its tab label.
</Tip>

<CodeGroup>

```java HelloWorld.java example icon=java lines
class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
```

````mdx Format
```java HelloWorld.java example lines icon="java"
class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
```
````

</CodeGroup>

## Code block options

Add meta options to your code blocks to customize their appearance.

<Note>
  You must specify a programming language for a code block before adding any other meta options.
</Note>

### Option syntax

- **String and boolean options**: Wrap with `""`, `''`, or no quotes.
- **Expression options**: Wrap with `{}`, `""`, or `''`.

### Syntax highlighting

Enable syntax highlighting by specifying the programming language after the opening backticks of a code block.

Mintlify uses [Shiki](https://shiki.style/) for syntax highlighting and supports all available languages. See the full list of [languages](https://shiki.style/languages) in Shiki's documentation.

Customize code block themes globally using `styling.codeblocks` in your `docs.json` file. Set simple themes like `system` or `dark`, or configure custom [Shiki themes](https://shiki.style/themes) for light and dark modes. See [Settings](/organize/settings-appearance#styling) for configuration options.

<CodeGroup>

```java Syntax highlighting example
class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
```

````mdx Format
```java Syntax highlighting example
class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
```
````

</CodeGroup>

<Accordion title="Custom syntax highlighting theme">
  For custom themes, set your theme in `docs.json` to `"css-variables"` and override syntax highlighting colors using CSS variables with the `--mint-` prefix.

  The following variables are available:

  **Basic colors**

  - `--mint-color-text`: Default text color
  - `--mint-color-background`: Background color

  **Token colors**

  - `--mint-token-constant`: Constants and literals
  - `--mint-token-string`: String values
  - `--mint-token-comment`: Comments
  - `--mint-token-keyword`: Keywords
  - `--mint-token-parameter`: Function parameters
  - `--mint-token-function`: Function names
  - `--mint-token-string-expression`: String expressions
  - `--mint-token-punctuation`: Punctuation marks
  - `--mint-token-link`: Links

  **ANSI colors**

  - `--mint-ansi-black`, `--mint-ansi-black-dim`
  - `--mint-ansi-red`, `--mint-ansi-red-dim`
  - `--mint-ansi-green`, `--mint-ansi-green-dim`
  - `--mint-ansi-yellow`, `--mint-ansi-yellow-dim`
  - `--mint-ansi-blue`, `--mint-ansi-blue-dim`
  - `--mint-ansi-magenta`, `--mint-ansi-magenta-dim`
  - `--mint-ansi-cyan`, `--mint-ansi-cyan-dim`
  - `--mint-ansi-white`, `--mint-ansi-white-dim`
  - `--mint-ansi-bright-black`, `--mint-ansi-bright-black-dim`
  - `--mint-ansi-bright-red`, `--mint-ansi-bright-red-dim`
  - `--mint-ansi-bright-green`, `--mint-ansi-bright-green-dim`
  - `--mint-ansi-bright-yellow`, `--mint-ansi-bright-yellow-dim`
  - `--mint-ansi-bright-blue`, `--mint-ansi-bright-blue-dim`
  - `--mint-ansi-bright-magenta`, `--mint-ansi-bright-magenta-dim`
  - `--mint-ansi-bright-cyan`, `--mint-ansi-bright-cyan-dim`
  - `--mint-ansi-bright-white`, `--mint-ansi-bright-white-dim`

  **Custom syntax highlighting**

  Add syntax highlighting for languages not included in Shiki's default set by providing custom TextMate grammar files. Create a JSON file following the [TextMate grammar format](https://macromates.com/manual/en/language_grammars), then reference it in your `docs.json`. You can add multiple custom languages by including additional paths in the array.

  ```json docs.json
  {
    "styling": {
      "codeblocks": {
        "languages": {
          "custom": ["/languages/my-custom-language.json"]
        }
      }
    }
  }
  ```

</Accordion>

### Twoslash

In JavaScript and TypeScript code blocks, use `twoslash` to enable interactive type information. Users can hover over variables, functions, and parameters to see types and errors like in an IDE.

<CodeGroup>

```ts twoslash Twoslash example
type Pet = "cat" | "dog" | "hamster";

function adoptPet(name: string, type: Pet) {
  return `${name} the ${type} is now adopted!`;
}

// Hover to see the inferred types
const message = adoptPet("Mintie", "cat");
```

````mdx Format
```ts twoslash Twoslash example
type Pet = "cat" | "dog" | "hamster";

function adoptPet(name: string, type: Pet) {
  return `${name} the ${type} is now adopted!`;
}

// Hover to see the inferred types
const message = adoptPet("Mintie", "cat");
```
````

</CodeGroup>

### Title

Add a title to label your code example. Place the title after the language identifier. Titles can contain multiple words and file paths.

You can set the title two ways:

- **Inline**: Place the title directly after the language identifier.
- **`title` property**: Use `title="Your title"` for titles that need special characters or explicit quoting.

<CodeGroup>

```javascript Example title
const hello = "world";
```

```javascript title="utils/hello.js"
const hello = "world";
```

````mdx Inline format
```javascript Example title
const hello = "world";
```
````

````mdx title property format
```javascript title="utils/hello.js"
const hello = "world";
```
````

</CodeGroup>

### Icon

Add an icon to your code block using the `icon` property. See [Icons](/components/icons) for all available options.

<CodeGroup>

```javascript Icon example icon=square-js
const hello = "world";
```

````mdx Format
```javascript Icon example icon="square-js"
const hello = "world";
```
````

</CodeGroup>

### Line highlighting

Highlight specific lines in your code blocks using `highlight` with the line numbers or ranges you want to highlight.

<CodeGroup>

```javascript Line highlighting example {1,2,5}
const greeting = "Hello, World!";
function sayHello() {
  console.log(greeting);
}
sayHello();
```

````mdx Format
```javascript Line highlighting example highlight={1-2,5}
const greeting = "Hello, World!";
function sayHello() {
  console.log(greeting);
}
sayHello();
```
````

</CodeGroup>

### Line focusing

Focus on specific lines in your code blocks using `focus` with line numbers or ranges.

<CodeGroup>

```javascript Line focusing example focus=2,4,5
const greeting = "Hello, World!";
function sayHello() {
  console.log(greeting);
}
sayHello();
```

````mdx Format
```javascript Line focusing example focus={2,4-5}
const greeting = "Hello, World!";
function sayHello() {
  console.log(greeting);
}
sayHello();
```
````

</CodeGroup>

### Show line numbers

Display line numbers on the left side of your code block using `lines`.

<CodeGroup>

```javascript Show line numbers example lines
const greeting = "Hello, World!";
function sayHello() {
  console.log(greeting);
}
sayHello();
```

````mdx Format
```javascript Show line numbers example lines
const greeting = "Hello, World!";
function sayHello() {
  console.log(greeting);
}
sayHello();
```
````

</CodeGroup>

### Expandable

Allow users to expand and collapse long code blocks using `expandable`.

<CodeGroup>

```python Expandable example expandable
from datetime import datetime, timedelta
from typing import Dict, List, Optional
from dataclasses import dataclass

@dataclass
class Book:
title: str
author: str
isbn: str
checked_out: bool = False
due_date: Optional[datetime] = None

class Library:
    def __init__(self):
        self.books: Dict[str, Book] = {}
        self.checkouts: Dict[str, List[str]] = {} # patron -> list of ISBNs

    def add_book(self, book: Book) -> None:
        if book.isbn in self.books:
            raise ValueError(f"Book with ISBN {book.isbn} already exists")
        self.books[book.isbn] = book

    def checkout_book(self, isbn: str, patron: str, days: int = 14) -> None:
        if patron not in self.checkouts:
            self.checkouts[patron] = []

        book = self.books.get(isbn)
        if not book:
            raise ValueError("Book not found")

        if book.checked_out:
            raise ValueError("Book is already checked out")

        if len(self.checkouts[patron]) >= 3:
            raise ValueError("Patron has reached checkout limit")

        book.checked_out = True
        book.due_date = datetime.now() + timedelta(days=days)
        self.checkouts[patron].append(isbn)

    def return_book(self, isbn: str) -> float:
        book = self.books.get(isbn)
        if not book or not book.checked_out:
            raise ValueError("Book not found or not checked out")

        late_fee = 0.0
        if datetime.now() > book.due_date:
            days_late = (datetime.now() - book.due_date).days
            late_fee = days_late * 0.50

        book.checked_out = False
        book.due_date = None

        # Remove from patron's checkouts
        for patron, books in self.checkouts.items():
            if isbn in books:
                books.remove(isbn)
                break

        return late_fee

    def search(self, query: str) -> List[Book]:
        query = query.lower()
        return [
            book for book in self.books.values()
            if query in book.title.lower() or query in book.author.lower()
        ]

def main():
    library = Library()

    # Add some books
    books = [
        Book("The Hobbit", "J.R.R. Tolkien", "978-0-261-10295-4"),
        Book("1984", "George Orwell", "978-0-452-28423-4"),
    ]

    for book in books:
        library.add_book(book)

    # Checkout and return example
    library.checkout_book("978-0-261-10295-4", "patron123")
    late_fee = library.return_book("978-0-261-10295-4")
    print(f"Late fee: ${late_fee:.2f}")

if __name__ == "__main__":
    main()
```

````text Format
```python Expandable example expandable
from datetime import datetime, timedelta
from typing import Dict, List, Optional
from dataclasses import dataclass

# ...

if __name__ == "__main__":
    main()
```
````

</CodeGroup>

### Wrap

Enable text wrapping for long lines using `wrap`. This prevents horizontal scrolling and makes long lines easier to read.

<CodeGroup>

```javascript Wrap example wrap
const greeting =
  "Hello, World! I am a long line of text that will wrap to the next line.";
function sayHello() {
  console.log(greeting);
}
sayHello();
```

````mdx Format
```javascript Wrap example wrap
const greeting =
  "Hello, World! I am a long line of text that will wrap to the next line.";
function sayHello() {
  console.log(greeting);
}
sayHello();
```
````

</CodeGroup>

### Hide copy button

Use the `nocopy` flag to hide the copy to clipboard button on a code block. This can be useful for content where copying is not meaningful, like ASCII diagrams or terminal output.

Pass `nocopy="false"` to explicitly show the copy button. For a code block with no language, use ` ```nocopy ` on its own to render the block as plain text without a copy button.

Inside a `<CodeGroup>`, you can define the visibility of the copy button for each tab.

<CodeGroup>

```text title="No copy example" nocopy
User ──▶ CDN ──▶ Origin
              │
              └──▶ Cache
```

````mdx Format
```text title="No copy example" nocopy
User ──▶ CDN ──▶ Origin
              │
              └──▶ Cache
```
````

</CodeGroup>

### Diff

Show a visual diff of added or removed lines in your code blocks. The visual diff highlights added lines in green and removed lines in red.

Add `[!code ++]` or `[!code --]` inside a comment at the end of a line to mark it as added or removed. Use your language's comment syntax:

| Language | Added | Removed |
| --- | --- | --- |
| JavaScript, TypeScript, Java, C, C++, Go, Rust | `// [!code ++]` | `// [!code --]` |
| Python, Ruby, Bash, YAML | `# [!code ++]` | `# [!code --]` |
| HTML, XML | `<!-- [!code ++] -->` | `<!-- [!code --] -->` |
| CSS | `/* [!code ++] */` | `/* [!code --] */` |
| SQL, Lua | `-- [!code ++]` | `-- [!code --]` |

For multiple consecutive lines, add a colon and the number of lines:

- `// [!code ++:3]`: Mark the current line plus the next two lines as added.
- `# [!code --:5]`: Mark the current line plus the next four lines as removed.

<CodeGroup>

```js JavaScript diff lines
const greeting = "Hello, World!"; // [!code ++]
function sayHello() {
  console.log("Hello, World!"); // [!code --]
  console.log(greeting); // [!code ++]
}
sayHello();
```

```python Python diff lines
def greet():
    print("Hello, World!")  # [!code --]
    print("Hello, Mintlify!")  # [!code ++]

greet()
```

````text JavaScript format
```js JavaScript diff lines
const greeting = "Hello, World!"; // [!code ++]
function sayHello() {
  console.log("Hello, World!"); // [!code --]
  console.log(greeting); // [!code ++]
}
sayHello();
```
````

````text Python format
```python Python diff lines
def greet():
    print("Hello, World!")  # [!code --]
    print("Hello, Mintlify!")  # [!code ++]

greet()
```
````

</CodeGroup>

## CodeBlock component

Use the `<CodeBlock>` component in custom React components to programmatically render code blocks with the same styling and features as markdown code blocks.

### Props

<ResponseField name="language" type="string">
  The programming language for syntax highlighting.
</ResponseField>

<ResponseField name="filename" type="string">
  The filename to display in the code block header.
</ResponseField>

<ResponseField name="icon" type="string">
  The icon to display in the code block header. See [Icons](/components/icons)
  for available options.
</ResponseField>

<ResponseField name="lines" type="boolean">
  Whether to show line numbers.
</ResponseField>

<ResponseField name="wrap" type="boolean">
  Whether to wrap the code block.
</ResponseField>

<ResponseField name="nocopy" type="boolean">
  Whether to hide the copy-to-clipboard button.
</ResponseField>

<ResponseField name="expandable" type="boolean">
  Whether to expand the code block.
</ResponseField>

<ResponseField name="highlight" type="string">
  The lines to highlight. Provide a stringified array of numbers. Example:
  `"[1,3,4,5]"`.
</ResponseField>

<ResponseField name="focus" type="string">
  The lines to focus on. Provide a stringified array of numbers. Example:
  `"[1,3,4,5]"`.
</ResponseField>

### Example

```jsx
export const CustomCodeBlock = ({
  filename,
  icon,
  language,
  highlight,
  children,
}) => {
  return (
    <CodeBlock
      filename={filename}
      icon={icon}
      language={language}
      lines
      highlight={highlight}
    >
      {children}
    </CodeBlock>
  );
};
```