{
  "title": "Vigenère cipher encoder and decoder",
  "human_url": "https://happytails.ai/en/text-tools/vigenere-cipher/",
  "agent_url": "https://happytails.ai/agents/en/text-tools/vigenere-cipher/",
  "language": "en",
  "markdown_url": "https://happytails.ai/en/text-tools/vigenere-cipher.md",
  "content": "Vigenère cipher encoder and decoder\nMake a repeating-key letter cipher for a puzzle or lesson.\nHow can we improve this tool?\nReport a problem or share an idea.\nPlease leave out private information. Your message and the tool name go to our team via PostHog.\nHow to use Vigenère cipher encoder and decoder\nEnter your message, a key containing letters A–Z, and choose Encode or Decode. The key repeats across letters only; spaces and punctuation do not consume a key character.\nATTACK AT DAWN with key LEMON becomes LXFOPV EF RNHR. Choose Decode with the same key to restore it.\nUseful next steps\nCaesar cipher encoder and decoder\nMorse code translator\nUppercase\nHow to use it\nEnter your message, a key containing letters A–Z, and choose Encode or Decode. The key repeats across letters only; spaces and punctuation do not consume a key character.\nTry a small example\nATTACK AT DAWN with key LEMON becomes LXFOPV EF RNHR. Choose Decode with the same key to restore it.\nWhat to know\nRepeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.",
  "content_format": "text/plain",
  "visibility": "public",
  "links": [
    {
      "name": "Caesar cipher encoder and decoder",
      "url": "https://happytails.ai/en/text-tools/caesar-cipher/"
    },
    {
      "name": "Morse code translator",
      "url": "https://happytails.ai/en/text-tools/morse-code-translator/"
    },
    {
      "name": "Uppercase",
      "url": "https://happytails.ai/en/text-tools/uppercase/"
    }
  ],
  "tool": {
    "id": "vigenere-cipher",
    "category": "text-tools",
    "built": true,
    "requirements": "Repeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.",
    "implementation": {
      "fields": [
        {
          "key": "key",
          "label": "Key (letters A–Z)",
          "value": "LEMON",
          "type": "text"
        },
        {
          "key": "direction",
          "label": "Direction",
          "value": "Encode",
          "type": "select",
          "values": [
            "Encode",
            "Decode"
          ]
        }
      ],
      "live": true,
      "note": "Repeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.",
      "experience": {
        "automatic": true,
        "single": false,
        "inputMaxLength": 1000000,
        "inputMode": "text",
        "label": "Your text",
        "placeholder": "Type or paste your input…",
        "help": "Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.",
        "action": null
      },
      "mode": "automatic",
      "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"
    }
  },
  "markdown": "# Vigenère cipher encoder and decoder\n\n- Human page: https://happytails.ai/en/text-tools/vigenere-cipher/\n- Markdown: https://happytails.ai/en/text-tools/vigenere-cipher.md\n- Structured JSON: https://happytails.ai/agents/en/text-tools/vigenere-cipher/index.json\n- Visibility: public\n\n## Tool capabilities\n\n| Property | Value |\n| --- | --- |\n| Tool ID | `vigenere-cipher` |\n| Category | text-tools |\n| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |\n| Browser execution | Automatic updates after valid input or file selection. |\n| Browser processing | Browser; see tool notes for network behavior. |\n| HTTP API | Not callable through HTTP. |\n| Browser-agent interface | run_current_tool |\n\n### Implementation notes\n\nRepeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.\n\n### Inputs and settings\n\nText input: Your text.\n\nExample or placeholder shown in the interface (not a validated fixture):\n\n```text\nType or paste your input…\n```\n\nChange the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.\n\n| Setting | Meaning | Control type | Default | Constraints |\n| --- | --- | --- | --- | --- |\n| `key` | Key (letters A–Z) | text | \"LEMON\" |  |\n| `direction` | Direction | select | \"Encode\" | Allowed: Encode, Decode |\n\n### Browser-agent workflow\n\n1. Open the human page in a browser that supports WebMCP.\n2. Discover the interface exposed by that page; use its actual schema.\n3. Select files on the page first when the tool requires files.\n4. Call `run_current_tool` with valid input and settings.\n5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.\n\nCalls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.\n\n### Planning specification\n\nRepeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.\n\nThis describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.\n\n### Complete machine-readable capability record\n\n```json\n{\n  \"id\": \"vigenere-cipher\",\n  \"category\": \"text-tools\",\n  \"built\": true,\n  \"requirements\": \"Repeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.\",\n  \"implementation\": {\n    \"fields\": [\n      {\n        \"key\": \"key\",\n        \"label\": \"Key (letters A–Z)\",\n        \"value\": \"LEMON\",\n        \"type\": \"text\"\n      },\n      {\n        \"key\": \"direction\",\n        \"label\": \"Direction\",\n        \"value\": \"Encode\",\n        \"type\": \"select\",\n        \"values\": [\n          \"Encode\",\n          \"Decode\"\n        ]\n      }\n    ],\n    \"live\": true,\n    \"note\": \"Repeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.\",\n    \"experience\": {\n      \"automatic\": true,\n      \"single\": false,\n      \"inputMaxLength\": 1000000,\n      \"inputMode\": \"text\",\n      \"label\": \"Your text\",\n      \"placeholder\": \"Type or paste your input…\",\n      \"help\": \"Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.\",\n      \"action\": null\n    },\n    \"mode\": \"automatic\",\n    \"interactive\": false\n  },\n  \"execution\": \"Browser interface\",\n  \"api\": null,\n  \"browser_agent\": {\n    \"supported\": true,\n    \"name\": \"run_current_tool\",\n    \"discovery\": \"WebMCP on the human page in a supporting browser\",\n    \"verification\": \"See audit/API-AUDIT.md; availability is not verification\"\n  }\n}\n```\n\n## Page guide\n\nMake a repeating-key letter cipher for a puzzle or lesson.\n\nHow can we improve this tool?\n\nReport a problem or share an idea.\n\nPlease leave out private information. Your message and the tool name go to our team via PostHog.\n\n### How to use Vigenère cipher encoder and decoder\n\n1. Enter your message, a key containing letters A–Z, and choose Encode or Decode. The key repeats across letters only; spaces and punctuation do not consume a key character.\n2. ATTACK AT DAWN with key LEMON becomes LXFOPV EF RNHR. Choose Decode with the same key to restore it.\n\n## Useful next steps\n\n- [Caesar cipher encoder and decoder](https://happytails.ai/en/text-tools/caesar-cipher/) ([Markdown](https://happytails.ai/en/text-tools/caesar-cipher.md))\n\n- [Morse code translator](https://happytails.ai/en/text-tools/morse-code-translator/) ([Markdown](https://happytails.ai/en/text-tools/morse-code-translator.md))\n\n- [Uppercase](https://happytails.ai/en/text-tools/uppercase/) ([Markdown](https://happytails.ai/en/text-tools/uppercase.md))\n\n## How to use it\n\nEnter your message, a key containing letters A–Z, and choose Encode or Decode. The key repeats across letters only; spaces and punctuation do not consume a key character.\n\n### Try a small example\n\nATTACK AT DAWN with key LEMON becomes LXFOPV EF RNHR. Choose Decode with the same key to restore it.\n\n### What to know\n\nRepeats a letter key over A–Z; spaces and punctuation do not advance the key. For puzzles and learning only. It is not secure encryption.\n"
}