tail-fweb

tail -f — but in a browser.

Stream any log file to a live web UI. Use it as a standalone CLI or embed it directly into your Express app.

Features

• Live stream — new lines pushed over WebSockets the instant they're written
• History replay — opening a new tab shows all buffered lines immediately
• Search & filter — type to filter; matches are highlighted inline
• Pause scroll — freeze the viewport while new lines buffer silently (Space to resume)
• Line wrap toggle — switch long lines between horizontal scroll and wrapped, remembers your choice
• Log-level colours — ERROR/FATAL rows tinted red, WARN amber, out of the box
• Copy & clear — clipboard copy of visible lines; one-click clear
• Embeddable — mounts as an Express Router on any path in your existing app

Install

# global CLI
npm install -g tail-fweb

# or add to your project
npm install tail-fweb

Usage

CLI

tail-fweb -f app.log
# → http://localhost:3000/tail-f

tail-fweb -f /var/log/nginx/access.log -p 8080
# → http://localhost:8080/tail-f

| Flag | Default | Description | |------|---------|-------------| | -f, --filename | (required) | Path to the file to watch | | -p, --port | 3000 | Port to listen on |

Embed in an Express app

const express  = require('express');
const tailFweb = require('tail-fweb');

const app = express();

app.use('/logs', tailFweb('./app.log'));

app.listen(3000);
// viewer → http://localhost:3000/logs

Mount multiple files on different paths:

app.use('/logs/access',  tailFweb('/var/log/nginx/access.log',  { title: 'Access' }));
app.use('/logs/error',   tailFweb('/var/log/nginx/error.log',   { title: 'Errors' }));
app.use('/logs/app',     tailFweb('./app.log',                  { title: 'App',  maxLines: 2000 }));

How embedding works

tailFweb() returns a standard Express Router. On the first incoming request it reads req.socket.server to attach socket.io to your existing HTTP server — no second port, no separate process. The file watcher starts at the same time.

API

tailFweb(filename, [options])

| Parameter | Type | Description | |-----------|------|-------------| | filename | string | Path to the file to watch (required) | | options.title | string | Browser tab / page title (default: 'tail-fweb') | | options.maxLines | number | Lines to keep in memory for late-joining connections (default: 5000) |

Returns an Express Router. Mount it with app.use(path, router).

Requirements

• Node.js ≥ 18
• Express ≥ 4 (peer dependency when embedding)

License

MIT © Abhijeet Apsunde