Rainbow Indent Guide

🌈 Multi-level rainbow indent guides for Eclipse — a fork of Indent Guide, rebuilt to work on current releases. 🌈

Deep nesting — one colour per level, so eight levels stay readable.	Active block — the guide holding the caret keeps its colour and lights up.
Rainbow parentheses — nine levels of nested calls, each bracket matched to its guide.	Restore blink — a greyed guide flashes as it takes its colour back.

• one color per indentation level (rainbow), cycled past the seventh
• the braces of a block are repainted in the color of its guide, so the two read as one shape, a comment written behind the brace included
• matching round parentheses are colored by nesting depth with their own configurable seven-color palette, independent from braces and guides
• click a guide to light and pin it; a click away from every guide releases it. The lit guide keeps the color of its level and turns it up — brighter and deeper, not washed out towards white
• following the caret is optional and disabled by default
• guides follow the brace structure: they start below the line opening the block and reach the brace closing it
• a multi-line call gets one guide, at the indentation of the line opening it: the columns its continuation lines are aligned to are alignment, not nesting, and the guides of the blocks around it run through unbroken
• blank lines and comments no longer break the vertical lines
• backspace at the indentation of a comment written under a brace can move it onto the line above, instead of shaving a level off an indentation that was already right. The same for code written hard against a brace. Both halves are off until they are asked for: a backspace that moves a line is a change to what the key does. A brace on a line of its own never moves: it keeps walking left to the level of the block it closes
• each guide is stroked in one piece over the lines it spans, so thin or barely opaque lines stay clean instead of breaking up into dots
• sub-pixel guide placement, so the lines do not drift right on deep levels when DPI scaling is on
• greying of the single guide that does not line up with the brace opening or closing its block; when the indentation is fixed the guide blinks white for a moment as it takes its color back, over the lines of that block alone and not over every block sharing its column. A header spread over several lines, catch (A | B continued by | C e) {, opens where its statement does: the alignment of its continuation is not read as a wrong indentation
• the tabs restored with the workbench are painted at startup, without having to be closed and reopened
• the common content types (Java, XML, properties, JSP, HTML, CSS, JS, PHP, C/C++) are enabled out of the box

Everything is configurable under Window > Preferences > General > Editors > Text Editors > Indent Guide, with the colors on the Style subpage. Changes apply immediately, without reopening editors.

Drag the button onto a running Eclipse window. Requires the Marketplace Client, which most Eclipse packages ship with.

https://simoneplatania.github.io/RainbowIndentGuide/

1. Help > Install New Software...
2. Add..., paste the address, give it any name
3. tick Rainbow Indent Guide, then Next, accept the license, Finish
4. restart when prompted

Eclipse remembers the site and offers later versions under Help > Check for Updates.

For an installation with no network access. Download RainbowIndentGuide-1.2.5-updatesite.zip from the latest release. Don't unzip it.

1. Help > Install New Software...
2. Add... > Archive... and pick the zip
3. tick Rainbow Indent Guide, then Next, accept the license, Finish
4. restart when prompted

Eclipse will warn about unsigned content — the jar has no digital signature. Confirm and continue.

To uninstall: Help > About > Installation Details, select it, Uninstall.

Upgrading from another Indent Guide? Remove it first. This fork still contributes the extension ids of the original, so two of them installed side by side give duplicate preference pages and two painters drawing over each other. Since 1.1.0 p2 refuses the install rather than let that happen: the feature declares jp.sourceforge.pdt_tools.indentGuide and Certiv Analytics' net.certiv.tools.indentguide as conflicting, both as features and as bare bundles. Preferences are not carried over.

Tested on Eclipse 2020-06, 2024-09 and 2026-06. Compiled with javac --release 8, so it should also load on much older installations (3.6 and later) — an API newer than Java 8 fails at compile time rather than throwing NoSuchMethodError at runtime. Requires Java 8 or later.

Verified to work with Show only selected element and Clone Editor.

Bug reports welcome, especially from versions I haven't tested.

No guides in a file. Guides are drawn per content type, and matching is on exact equality, so a file only gets them if it is opened with the editor registered for its type. A .jsp on an Eclipse without WTP has no JSP content type and opens in the plain text editor, which is not the same thing as a JSP editor. Right-click → Open With shows which one is in use. Enabling Text in the preferences covers anything that falls back to the generic editor, at the cost of drawing guides in files where they are of little use.

No guides anywhere. Check Help > About > Installation Details > Plug-ins and look for alien.rainbow.indentguide. If it is listed as INSTALLED rather than ACTIVE, the bundle was found but could not be resolved; if it is not listed at all, it never got picked up — start Eclipse once with -clean.

Guides in the wrong place, or drawn twice. Another Indent Guide plug-in is probably still installed. Since 1.1.0 p2 refuses the install, but an older copy dropped into dropins/ bypasses p2 entirely and will keep painting.

Preference changes don't show up. They apply immediately to open editors. If nothing changes, the preference store is likely a different one — check you are not looking at a second workspace.

alien.rainbow.indentguide/         plug-in
alien.rainbow.indentguide.feature/ feature
docs/                              p2 repository, release JARs and ZIP
build.sh                           regenerates docs/ and the release zip

docs/ is the only copy of the update site, and it is what Help > Install New Software... reads over HTTP. Two things in it are load bearing and easy to lose: .nojekyll, without which GitHub runs the directory through Jekyll and drops anything starting with an underscore, and site.xml, which the publisher reads to decide what goes in the category.

To cut a release, bump Bundle-Version in the plug-in manifest and version in feature.xml to match, then:

./build.sh /path/to/eclipse

It compiles with --release 8, rebuilds both jars, rewrites the version in site.xml, republishes the p2 metadata and repacks the archive. It refuses to run if the two versions disagree.

The painting code originates from Eclipse's own WhitespaceCharacterPainter (Anton Leherbauer, Wind River Systems, and contributors), which was adapted into an indent guide as jp.sourceforge.pdt_tools.indentGuide, later re-uploaded by kiritsuku when the original repository disappeared. This fork starts from there. Gerald Rosenberg also maintains an active fork of the same plug-in.

This repository is a fork. The original work stays under the MIT License, Copyright (c) 2014 Simon Schaefer; parts of the painter derive from the Eclipse Platform and stay under the Eclipse Public License v1.0, Copyright (c) 2006, 2009 Wind River Systems, Inc., IBM Corporation and others. The modifications and new files contributed by this fork are Copyright (c) 2026 Simone Platania and are released under the Eclipse Public License v1.0.

The notices in the individual source files are authoritative. See LICENSE.