GPXWeaver

A powerful, web-based GPX track editor for simplifying, editing, splitting, and joining GPS tracks. Perfect for cleaning up recorded tracks from apps like GeoTracker before sharing or analyzing.

🔗 Live App: https://asg49.github.io/GPXWeaver/

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Features

⚡ Performance

• Fast load for massive files — tested with 500,000+ points in 120MB+ GPX files
• Toggle-only marker visibility — no automatic recalculation on zoom, fast zooming at any scale
• Clean default — only the track line is shown on load; markers appear only when you ask for them

📉 Track Simplification

• Douglas-Peucker algorithm for intelligent point reduction
• Manual simplification at any percentage (1–95%) — no auto-simplification
• Restore Original to undo simplification at any time
• Simplification respects your current marker visibility setting

📍 Points Visibility

• Manual toggle only — "●○ Points OFF / ● Points ON" button controls all marker display
• No automatic zoom-based marker loading — zoom freely without performance hits
• Marker colors: 🔴 Red (normal/delete mode) · 🟠 Orange (split mode)

✏️ Track Editing

• Drag points — move any point to adjust position (coordinates rounded to 6 decimal places)
• Add points — tap the track line to insert new waypoints with interpolated ele, time, speed, and course
• Delete points — long-press (2.6s) on any point to mark for deletion
• Rectangle Selection — draw a rectangle to bulk-select and delete multiple points (works on mobile and desktop)
• All edits update the track line in real time

✂️ Track Splitting

• Split mode — tap any point to divide the track at that location
• Save individual segments as separate GPX files
• Split markers auto-clean after save

🔗 Track Joining

• Smart multi-file loading — select 2+ files and they join automatically
• Geometric chaining — tracks are ordered by geographic proximity of endpoints, not by filename or selection order
• Starting track auto-identified as the one with no incoming connection
• Greedy nearest-neighbor chain eliminates stray connecting lines
• Select 1 file = load normally; select multiple = auto-chain and join

🌐 Gap Detection

• Logarithmic gap threshold slider (10m – 1,000km)
• Prevents unwanted connector lines between segments
• Adjustable in real time

🗺️ Map Layers

• OpenStreetMap
• OpenTopoMap (topographic contours)
• Google Terrain (default)
• Google Satellite
• Google Hybrid
• Esri World Imagery

📊 Navigation Controls

Desktop:

• Zoom display + Points toggle — bottom-left
• Scale bar — bottom-right
• Layer selector — top-right

Mobile:

• Zoom display — top-left (below +/− buttons)
• Points toggle — top-right
• Scale bar — bottom-right

💾 File Handling

• Save filename uses the actual disk filename you loaded, not the internal GPX track name
• Edited files get _X suffix (e.g. MyHike_X.gpx)
• Current filename displayed in header bar (updates to _X on first edit)
• Saved GPX always includes a <metadata> block with save filename and UTC timestamp
• All original <trkpt> data preserved on save: elevation, time, speed, course, extensions
• Coordinate precision: always 6 decimal places (~0.11m)
• GeoTracker extensions (<geotracker:meta c="course" s="speed"/>) fully preserved and interpolated for added points

🔒 Security

• HTML sanitization on all track name display (sanitizeHTML())
• XML sanitization on all GPX output (sanitizeXML())
• Protects against malicious GPX files with injected content

📱 Mobile-Optimized

• Responsive layout for phones and tablets
• Touch-friendly controls including rectangle selection
• Compact header with current filename displayed

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Usage

Getting Started

1. Load a GPX file — Menu (☰) → Load GPX File → select file(s)
   • Select multiple files to auto-chain and join them geometrically
2. View your track — blue line shown immediately; no markers until you ask
3. Show markers — click "●○ Points OFF" → becomes "● Points ON"
4. Edit — drag points, tap line to add, long-press to delete, or draw a rectangle to bulk-delete
5. Simplify — Menu → adjust slider → Apply Simplification → Restore Original if needed
6. Save — Menu → Save GPX → file saves with _X suffix using your original filename

Joining Multiple Google Maps Routes

1. Generate your route segments in Google Maps (max 10 waypoints each)
2. Convert each to GPX using maptogpx.com
3. Menu → Load GPX File → select all segment files at once
4. GPXWeaver automatically chains them in the correct geographic order
5. Review the join list, then Join All Tracks

Rectangle Selection (Bulk Delete)

1. Menu → Enable "Rectangle Select"
2. Draw a rectangle over the points you want to remove
3. Tap "Delete Selected" to remove them all at once

Splitting a Track

1. Menu → Enable "Split Mode"
2. Tap the point where you want to split
3. Save → downloads as separate GPX files

Gap Detection (Joined Tracks)

• Menu → adjust Gap Detection slider
• Increase to hide connector lines between segments
• Works in real time

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File Format

• Input: .gpx files (GPX 1.0 and 1.1)
• Output: GPX 1.1, all original <trkpt> data preserved (ele, time, speed, course, extensions)
• Metadata: <metadata> block added to every saved file with name and timestamp
• Coordinates: 6 decimal places in all output
• Namespaces: GeoTracker and other extension namespaces declared at root level

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Map Controls Summary

Control	Desktop	Mobile
Zoom +/−	top-left	top-left
Zoom display	bottom-left	top-left
Points toggle	bottom-left	top-right
Layer selector	top-right	top-right
Scale bar	bottom-right	bottom-right

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Technical Details

• Single HTML file — no dependencies to install, works offline after first load
• Leaflet.js mapping library
• Douglas-Peucker simplification algorithm
• Haversine distance formula for accurate geographic calculations
• Geometric nearest-neighbor chaining for correct multi-track join order
• All event listeners properly registered inside DOMContentLoaded
• XSS protection on all user-generated content inserted into HTML or XML

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Recent Improvements (v6.0–v6.7)

✅ v6.7 — Geometric chaining bug fix

• Critical fix: maxIncomingDist was initialized to Infinity instead of -Infinity
• Condition closestIncoming > Infinity is always false — starting track never updated
• Algorithm silently did nothing; tracks were always joined in browser file order
• One-character fix restores correct geometric chaining behavior ✓

✅ v6.6 — Geometric track chaining

• Replaced alphabetical sort with nearest-neighbor geographic chaining
• haversineDistance() for accurate endpoint distance calculation
• Starting track = the one whose first point has no close incoming endpoint
• Eliminates stray connecting lines from wrong join order
• Works regardless of browser file selection order or filename

✅ v6.5 — Gap slider initialization fix

• Gap Detection slider thumb was rendering at far right on load
• Added explicit initialization inside DOMContentLoaded
• Slider and label now correctly show 1.0 km on load

✅ v6.4 — Slider visibility

• accent-color: #3498db on both sliders for visibility on dark background

✅ v6.3 — Namespace fix

• Browser innerHTML was injecting redundant xmlns= on every <trkpt> child element
• Added cleanInnerXML() to strip redundant declarations before GPX output
• xmlns:geotracker declared at root <gpx> level (correct XML practice)
• Saved files now load cleanly in all GPX applications

✅ v6.2 — Event listeners & metadata

• All event listeners moved inside DOMContentLoaded (was causing menu/layer failures)
• GPX <metadata> block (filename + UTC timestamp) added to all saved files
• Coordinate precision fixed to 6 decimal places in all three GPX generators

✅ v6.1 — Coordinate precision

• Dragged and added points stored and output at 6 decimal places (was 15+)

✅ v6.0 — GeoTracker data preservation

• Full <trkpt> innerHTML preserved through all edit operations
• interpolateSpeed() and interpolateCourse() for added points
• Comprehensive code audit: XSS sanitization, dead code removal, logic fixes

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Changelog

v6.7 (2026-07-23)

• Fixed geometric chaining: maxIncomingDist initialized to -Infinity (was Infinity)
• Starting track now correctly identified; join order now truly geometric ✓

v6.6 (2026-07-23)

• Geometric nearest-neighbor track chaining replaces alphabetical sort
• haversineDistance() and geometricChainTracks() functions added
• 500m endpoint threshold handles GPS rounding between shared waypoints

v6.5 (2026-07-22)

• Gap Detection slider thumb now correctly initialized inside DOMContentLoaded
• accent-color added to both sliders for dark-background visibility

v6.4 (2026-07-22)

• Slider accent color fix

v6.3 (2026-07-20)

• cleanInnerXML() strips redundant xmlns from trkpt innerHTML before output
• xmlns:geotracker declared at root <gpx> element in all three generators
• Fixed read-back failure for files saved by v6.2

v6.2 (2026-07-19)

• All event listeners inside DOMContentLoaded (was causing menu/layer control failures)
• <metadata> block (filename + UTC timestamp) in all saved GPX files
• Coordinate precision fixed to toFixed(6) in generateGPXForTrack()
• CSS duplicate #header rule fixed (was hiding header bar)

v6.1 (2026-07-19)

• Dragged and added point coordinates rounded to 6 decimal places

v6.0 (2026-07-15)

• GeoTracker <geotracker:meta c="course" s="speed"/> extensions parsed and preserved
• interpolateSpeed() and interpolateCourse() for added points (0°/360° wrap handling)
• Major code audit: XSS sanitization, duplicate function removed, dead code cleaned

v5.99 (2026-07-15)

• All <trkpt> data preserved via innerHTML capture; all three GPX generators output it verbatim

v5.98 (2026-07-15)

• Filename displayed in header bar; updates on first edit; clears on track clear

v5.97 (2026-07-15)

• Save uses actual disk filename not internal GPX <name> tag

v5.96 (2026-07-15)

• sanitizeHTML() and sanitizeXML() added throughout
• Dead code, duplicate functions, unused constants removed
• Toggle-only rule enforced in all createMarkers() call sites

v5.95 (2026-07-15)

• Toggle-only point visibility; zoomend does safety cleanup only
• Fast zooming at any zoom level, no recalculation overhead

v5.94 (2026-06-24)

• Rectangle selection fixed on mobile (changedTouches instead of touches)

v5.87 (2026-06-18)

• Mobile controls: zoom top-left, toggle top-right, scale bottom-right

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License

MIT License — see LICENSE file for details.

Author

Tony Gozdz © 2026
Battery R&D Engineer · Serious GPX Geek 🗺️

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Tested with files from 100 to 500,000+ points (120MB+ GPX). Handles extreme files efficiently. All editing operations — drag, add, delete, rectangle select, split, join, simplify — work reliably on both mobile and desktop.