Language and Theme

The editor's own text comes in 25 languages, and its look is a theme: an appearance (System, Light, or Dark), a gray color, and an accent color.
Both belong to the person using the editor, not to the diagram. Neither is saved in the file, recorded in the undo history, or shared with collaborators, so each person sees their own, and changing either never marks a file modified.

Neither is on the Settings tab. The toolbar has a Theme button and, right after it, a Display Language button, both after the Find and Replace button. Quick Search lists Theme and Display Language on every tab.
The web app, Google Drive, VS Code, JetBrains IDEs, and Obsidian all offer both and remember your picks — see In Each Host. Both work in a read-only editor too.

Display Language

The language covers the editor's own text: toolbar tooltips, context menus, Quick Search, panels and dialogs, the Settings tab, the welcome screen, toasts and messages, and the placeholder an empty name, data type, default, or comment shows on the canvas and in an exported image.
It leaves these as written in every language: your table and column names, comments, and memos; database vendors, Code Generator languages, and file formats; data types, SQL keywords, and the ON DELETE and ON UPDATE actions; the Schema SQL options Create, If not exists, Drop & re-create, USE, and CREATE + USE; the marks PK, UQ, AI, N-N, NULL, and AK1.1; the name case and Bracket choices other than None; the names of keyboard keys; the theme builder's color names; generated SQL and code; and exported file names.

The languages, in the order the picker lists them:

In the picker	Language	Code
Bahasa Indonesia	Indonesian	id-ID
Deutsch	German	de-DE
English	English	en
Español	Spanish	es-ES
Euskara	Basque	eu-ES
Français	French	fr-FR
Italiano	Italian	it-IT
Nederlands	Dutch	nl-NL
Polski	Polish	pl-PL
Português	Portuguese	pt-PT
Português Brasileiro	Brazilian Portuguese	pt-BR
Română	Romanian	ro-RO
Slovenčina	Slovak	sk-SK
Slovenščina	Slovenian	sl-SI
Svenska	Swedish	sv-SE
Türkçe	Turkish	tr-TR
Русский	Russian	ru-RU
Українська	Ukrainian	uk-UA
עברית	Hebrew	he-IL
العربية	Arabic	ar-SA
فارسی	Persian	fa-IR
日本語	Japanese	ja-JP
简体中文	Simplified Chinese	zh-CN
繁體中文	Traditional Chinese	zh-TW
한국어	Korean	ko-KR

The Language that Quick Search offers on the Code Generator tab, and the Language row of the Lock list on the Settings tab, are the Code Generator's target language, not the display language.

Picking a Language

The Display Language button (a languages icon) opens the Display Language picker, a panel titled Display Language below the toolbar, over whichever tab is open.
System comes first, with the language it stands for right now beside it, and stays in view while the list scrolls. The 25 languages follow, each in its own name, and a check marks the option in force.

The panel opens with the keyboard on the checked row:

• ↑ and ↓ move through the rows and wrap around, and Home and End jump to the first and last.
• Enter or Space picks the focused row, as a click does.

A pick applies at once, closes the panel, and gives the keyboard back to the editor.

Close it without a pick with Escape, with the x button beside the title, whose tooltip reads Close (ESC), with a press anywhere in the editor outside the panel except on the toolbar, or with the Display Language button again.
Opening it closes the theme builder, Table Properties, and the Find and Replace panel. Opening Quick Search, the Find and Replace panel, or the theme builder closes it.

While the panel has the keyboard, a few editor shortcuts still work: Search, Find and Replace, Undo, Redo, Zoom In, Zoom Out, and Zoom Reset — see Shortcuts. Every other editor shortcut, the arrow keys, and Tab go no further than the panel, so the editor does not act on them. Keys the editor does not bind, such as the host's own save, reach the host as usual.

In Quick Search, Display Language lists System and the 25 languages, with a check on the option in force. A language is also found there by its English name or its code, so german or de-DE finds Deutsch.

What System Follows

System is where the language starts in the web app, Google Drive, VS Code, JetBrains IDEs, and Obsidian. It follows the host's language:

• In the web app, Google Drive, and your own page: the browser's preferred languages. A change to them is followed at once.
• In VS Code: VS Code's display language.
• In a JetBrains IDE: the language the IDE shows its own interface in.
• In Obsidian: Obsidian's language.

System takes the first of those languages the editor has, and English when it has none of them.
A regional variant counts as its language, so de-AT gives Deutsch and fr-CA gives Français. Chinese goes by script: a Traditional script gives 繁體中文 and any other script 简体中文. With no script named, Taiwan, Hong Kong, or Macau gives 繁體中文, and other Chinese gives 简体中文. Portuguese gives Português Brasileiro unless a region other than Brazil is named, so pt-PT gives Português; Obsidian's Portuguese also gives Português.

Right-to-left Languages

עברית (Hebrew), العربية (Arabic), and فارسی (Persian) lay the editor out right to left: the toolbar, the menus, the panels and dialogs, Quick Search, and the Settings tab are mirrored. A context menu's submenus open to the left, and the toolbar's Undo and Redo icons swap, so that Undo points back the way a right-to-left reader goes.

The diagram itself is never mirrored. The canvas with its tables, columns, relationships, and memos stays left to right, and so do the minimap, the scrollbars, the canvas toolbar, Visualization and its toolbar, the data type cells, the code on the Schema SQL and Code Generator tabs, the color picker, the diff viewer, time travel, and the Auto Layout preview.
The Find and Replace panel stays at the left edge of the canvas.
Names, comments, and other text you typed keep their own direction, so a Hebrew, Arabic, or Persian name reads right to left on the canvas as well.

Theme

The Theme button (a contrast icon) opens the theme builder, a panel titled Theme below the toolbar, over whichever tab is open. It has three parts:

• Accent color: 26 swatches. Each one's tooltip names it, such as indigo.
• Gray color: 6 swatches, gray, mauve, slate, sage, olive, and sand.
• Appearance: System, Light, and Dark.

The choice in force in each part is marked, and a pick applies at once while the builder stays open.
Picking a color leaves the appearance as it is, so a color picked under System keeps System.

System shows light or dark as the host does, and switches when the host does:

• In the web app, Google Drive, and your own page: the light or dark mode the browser reports, which follows the operating system.
• In VS Code: light under a light color theme, and dark under a dark one or either high contrast theme.
• In a JetBrains IDE: the IDE's light or dark theme.
• In Obsidian: Obsidian's light or dark theme.

Close the builder with Escape, with the x button beside the title, whose tooltip reads Close (ESC), with a press anywhere in the editor outside the panel except on the toolbar, or with the Theme button again.
Opening it closes Table Properties, the Display Language picker, and the Find and Replace panel. Opening Quick Search, the Find and Replace panel, or the Display Language picker closes it.
The builder holds no keys back, so the editor's shortcuts work while it is open.

In Quick Search, Theme lists System, Light, and Dark, with a check on the appearance in force. Picking one changes the appearance alone and leaves the gray and accent colors as they are.

In Each Host

What you pick in the editor, from the toolbar or Quick Search, is saved where the host keeps it, and every open diagram follows a change to it at once, wherever it is made.
In VS Code, a JetBrains IDE, and Obsidian, the host's Auto (the value auto in VS Code) is the editor's System. Picking System stores Auto, and picking Light or Dark stores that appearance, even when Auto was showing it already.
The extension's and the plugins' own settings and notices are in English whatever the display language.

Web App and Google Drive

On erd-editor.io, its collaboration sessions included, and in Google Drive, one language and one theme serve the app and every diagram in it.
Both are kept in this browser, not in the schema or the Drive file, and every erd-editor.io tab shares them: a pick in one tab changes the others at once.

The language is System, which follows the browser's preferred languages, until you pick one.
The app's own text, such as the sidebar, the trash, collaboration, and the Google Drive screens, follows the same language, and in Hebrew, Arabic, and Persian the whole app is laid out right to left. The Privacy Policy, Terms of Service, and support pages stay in English.
Besides the editor's panel and Quick Search, the bottom row of the sidebar has a language button, whose tooltip reads Display Language, beside the Privacy and Terms links. Its menu lists System, with the language it stands for, and then the 25 languages.

The theme starts at System, with the gray color olive and the accent color jade.
Besides the theme builder and Quick Search, the bottom of the sidebar has three icon buttons, System, Light, and Dark: beside Trash on erd-editor.io, and beside Sign out in Google Drive. They set the same appearance as the builder.

VS Code

The extension's settings are under ERD Editor in VS Code's Settings:

Setting	Values	Default
dineug.erd-editor.locale	auto, or a code from the language table	auto
dineug.erd-editor.theme.appearance	auto, light, dark	auto
dineug.erd-editor.theme.grayColor	the six gray colors	slate
dineug.erd-editor.theme.accentColor	the 26 accent colors	indigo

The Settings editor lists the language setting as Auto and then each language by its own name. A value in settings.json that names no language reads as auto.
A theme pick in the editor writes all three theme settings. A pick is written where its setting is already set: the workspace folder, else the workspace, else the user settings.

JetBrains IDEs

Settings | Tools | ERD Editor has Appearance: (Auto, Light, Dark), Gray color:, Accent color:, and Display language: (Auto, then each language by its own name), kept for the whole IDE.
They start at Auto, Slate, Indigo, and Auto.

Obsidian

Settings → ERD Editor has Appearance (Auto, Light, Dark), Gray color, Accent color, and Display language (Auto, then each language by its own name), kept per vault.
They start at Auto, Slate, Indigo, and Auto.
A change applies to every ERD tab of the vault, those in popout windows included.

Your Own Page

An <erd-editor> in your own page shows no Theme or Display Language button, and Quick Search lists neither, until the page turns them on with enableThemeBuilder and enableLocalePicker.
Until the page sets a language or the reader picks one, the editor shows English, or follows System while enableLocalePicker is on.
The theme starts at Dark, with the gray color slate and the accent color indigo, unless the page sets another or turns on systemDarkMode.
A reader's pick applies at once, but the element saves neither choice: the page sets the starting ones and saves the reader's picks itself — see Theme and Display Language in the API.