# Hex file viewer

- Human page: https://happytails.ai/en/developer-tools/hex-file-viewer/
- Markdown: https://happytails.ai/en/developer-tools/hex-file-viewer.md
- Structured JSON: https://happytails.ai/agents/en/developer-tools/hex-file-viewer/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `hex-file-viewer` |
| Category | developer-tools |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Use the visible action or interactive controls. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | Not callable through HTTP. |
| Browser-agent interface | run_current_tool |

### Implementation notes

Files are inspected on your device and are never modified. Maximum 256 MiB per file.

### Inputs and settings

No free-text input is required. Use the file inputs and/or settings below.

Accepted browser files: `See implementation notes`. Choose one file.

Browser file-input limit: 268435456 bytes in total. HTTP limits can differ.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `offset` | Starting byte offset | number | 0 | min=0 max=268435456 step=1 |
| `window` | Bytes to display | number | 1024 | min=16 max=4096 step=1 |
| `pattern` | Find hex bytes (optional) | text | "" |  |

### Browser-agent workflow

1. Open the human page in a browser that supports WebMCP.
2. Discover the interface exposed by that page; use its actual schema.
3. Select files on the page first when the tool requires files.
4. Call `run_current_tool` with valid input and settings.
5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.

Calls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.

### Planning specification

One file up to 256 MiB. View 16–4,096 bytes at a time. Search for 1–64 hexadecimal bytes from the chosen offset. Non-printable bytes appear as dots in the ASCII column; this is not a text-decoding or editing tool.

This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.

### Complete machine-readable capability record

```json
{
  "id": "hex-file-viewer",
  "category": "developer-tools",
  "built": true,
  "requirements": "One file up to 256 MiB. View 16–4,096 bytes at a time. Search for 1–64 hexadecimal bytes from the chosen offset. Non-printable bytes appear as dots in the ASCII column; this is not a text-decoding or editing tool.",
  "implementation": {
    "fields": [
      {
        "key": "offset",
        "label": "Starting byte offset",
        "value": 0,
        "type": "number",
        "min": 0,
        "max": 268435456,
        "step": 1
      },
      {
        "key": "window",
        "label": "Bytes to display",
        "value": 1024,
        "type": "number",
        "min": 16,
        "max": 4096,
        "step": 1
      },
      {
        "key": "pattern",
        "label": "Find hex bytes (optional)",
        "value": "",
        "type": "text",
        "help": "Enter 1–64 bytes, for example 48 65 6c 6c 6f. Search starts at the selected offset; the result window moves to the first match."
      }
    ],
    "files": true,
    "input": false,
    "multiple": false,
    "maxFileBytes": 268435456,
    "presentation": "metrics",
    "deferImagePreview": true,
    "note": "Files are inspected on your device and are never modified. Maximum 256 MiB per file.",
    "experience": {
      "automatic": false,
      "single": false,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Your text",
      "placeholder": "Type or paste your input…",
      "help": "Up to 1,000,000 characters. Review the settings before running.",
      "action": null
    },
    "mode": "explicit",
    "interactive": false
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}
```

## Page guide

Inspect a window of raw file bytes with hexadecimal values, absolute offsets and a readable ASCII column.

How can we improve this tool?

Report a problem or share an idea.

Please leave out private information. Your message and the tool name go to our team via PostHog.

### How to use Hex file viewer

1. Choose the local file or files.
2. Review the action and limits, then run the inspection.
3. Check the result and download a separate output or report.

## Useful next steps

- [Byte order mark editor](https://happytails.ai/en/developer-tools/byte-order-mark-editor/) ([Markdown](https://happytails.ai/en/developer-tools/byte-order-mark-editor.md))

- [Line ending auditor](https://happytails.ai/en/developer-tools/line-ending-auditor/) ([Markdown](https://happytails.ai/en/developer-tools/line-ending-auditor.md))

- [File hash](https://happytails.ai/en/developer-tools/file-hash/) ([Markdown](https://happytails.ai/en/developer-tools/file-hash.md))

## Choose a byte window

Set the starting byte offset and window size. Offsets are absolute and start at zero.

### Find a byte sequence

Optionally enter a hexadecimal sequence such as 48 65 6c 6c 6f. Search can cross read-chunk boundaries and moves to the first match.

### Read without modifying

Compare the byte values and ASCII representation. Download the visible window and its metadata without changing the source.