# Subtitle Merge — MCP tool `findutils:subtitle_merge`

Join several SubRip (.srt) or WebVTT (.vtt) caption files into one track. Append (the default) lays the files end to end: each later file is offset past the previous one's last cue, plus an optional gap, so parts exported separately — which normally restart at 00:00:00 — become one continuous timeline, and the cues are renumbered from 1. Dual stacks two files on one timeline instead, keeping the primary file's timing and appending each secondary cue's lines to the cue it overlaps, which is how a bilingual subtitle track is built. Inputs may mix the two formats; each is parsed natively and the output is written in one format. A file that cannot be parsed is reported by position and the rest still merge. Cue text is never translated or edited.

- Category: media
- MCP server: https://mcp.findutils.com/ (Streamable HTTP, no API keys, 120 req/min per IP)
- REST endpoint: POST https://api.findutils.com/api/tools/subtitle-merge/execute (no API keys, 60 req/min per IP)
- Reference page: https://findutils.com/mcp/subtitle-merge/
- Same tool on the other surface: https://findutils.com/api/subtitle-merge/

## Connect

```bash
claude mcp add findutils --transport http https://mcp.findutils.com/
```

Claude Desktop (`claude_desktop_config.json`):

```json
{
  "mcpServers": {
    "findutils": {
      "url": "https://mcp.findutils.com/"
    }
  }
}
```

## Call the tool (verified example)

```bash
curl -X POST https://mcp.findutils.com/ \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/call",
    "params": {
      "name": "subtitle_merge",
      "arguments": {
        "inputs": [
          "1\n00:00:01,000 --> 00:00:04,000\nPart one, first line.\n\n2\n00:00:05,000 --> 00:00:10,000\nPart one, last line.\n",
          "1\n00:00:00,500 --> 00:00:03,000\nPart two, first line.\n\n2\n00:00:04,000 --> 00:00:08,000\nPart two, last line.\n"
        ],
        "mode": "append",
        "gap_ms": 0
      }
    }
  }'
```

## Input schema

| Argument | Type | Required | Description |
|---|---|---|---|
| `inputs` | array | yes | Caption file contents, one string per file, in the order they should appear. At most 20. |
| `mode` | string (append \| dual) | no | append lays the files end to end on one continuous timeline. dual stacks them on the primary file's timing for a bilingual track. Default append. Default: `"append"`. |
| `gap_ms` | integer | no | Silence inserted between parts in append mode, in milliseconds. Ignored in dual mode. 0 to 60000. Default 0. Default: `0`. |
| `format` | string (auto \| srt \| vtt) | no | Output format. auto keeps the format of the first file that parsed. Default auto. Default: `"auto"`. |
| `primary` | integer | no | Dual mode only: the 0-based index of the file whose timing is kept. Default 0, the first file. Default: `0`. |
| `keep_absolute` | boolean | no | Append mode only: the files already share one timeline, so keep every timestamp as written and interleave the cues by start time instead of offsetting. Use this when the parts were cut from one long recording without being renumbered. Default false. Default: `false`. |

Example arguments (verified):

```json
{
  "inputs": [
    "1\n00:00:01,000 --> 00:00:04,000\nPart one, first line.\n\n2\n00:00:05,000 --> 00:00:10,000\nPart one, last line.\n",
    "1\n00:00:00,500 --> 00:00:03,000\nPart two, first line.\n\n2\n00:00:04,000 --> 00:00:08,000\nPart two, last line.\n"
  ],
  "mode": "append",
  "gap_ms": 0
}
```

## Also a REST endpoint

```bash
curl -X POST https://api.findutils.com/api/tools/subtitle-merge/execute \
  -H "Content-Type: application/json" \
  -d '{
    "inputs": [
      "1\n00:00:01,000 --> 00:00:04,000\nPart one, first line.\n\n2\n00:00:05,000 --> 00:00:10,000\nPart one, last line.\n",
      "1\n00:00:00,500 --> 00:00:03,000\nPart two, first line.\n\n2\n00:00:04,000 --> 00:00:08,000\nPart two, last line.\n"
    ],
    "mode": "append",
    "gap_ms": 0
  }'

# Parameter schema
curl https://api.findutils.com/api/tools/subtitle-merge
```

Full REST reference: https://findutils.com/api/subtitle-merge/ · OpenAPI 3.1 spec: https://findutils.com/api/openapi.json

---
Full catalog: POST https://mcp.findutils.com/ with method `tools/list` · https://findutils.com/mcp/ · https://findutils.com/llms.txt