Semantic Web Language Server

IDE support for Semantic Web languages — Turtle, TriG, N3, JSON-LD, and SPARQL. Autocompletion, diagnostics, formatting, SHACL validation, and more.

Table of Contents

• Features
• Installation
  • VS Code
  • NeoVim
• Configuration
• Documentation
• Screenshots

Features

Diagnostics

• Syntax errors — immediate feedback on malformed documents
• Undefined prefixes — flags uses of undeclared namespace prefixes
• SHACL shape violations — validates data against loaded SHACL shapes

Completion

• Prefix completion — typing foa expands to foaf: and inserts the prefix declaration
• Property completion — suggests properties ordered by domain relevance
• Class completion — when the predicate is a, suggests applicable classes

Hover

• Shows labels, descriptions, and class information for IRIs

Rename

• Rename terms local to the current file

Formatting

• Format Turtle, TriG, N3, and JSON-LD documents
• Enabled for Turtle by default; enable the others via swls.format.*

Semantic Highlighting

• Full semantic token highlighting for all supported languages

Installation

VS Code

Install from the Visual Studio Marketplace or Open VSX Registry.

On startup the extension looks for a native swls binary in its own directory (set swls.command to use a custom path instead). If no binary is found it falls back to a bundled WASM worker so the LSP is available immediately without any extra setup.

In the background it checks GitHub releases for updates. When a newer version is available you will be prompted to install it; after the download completes a window reload switches to the native binary.

NeoVim

A NeoVim plugin is available at SemanticWebLanguageServer/swls.nvim.

Configuration

All settings live under the swls prefix.

Setting	Type	Default	Description
swls.command	string	""	Path to the swls binary. If empty, the bundled binary in the extension directory is used
swls.forceWasm	boolean	false	Skip the native binary and always run the bundled WASM language server
swls.languages	string[]	["turtle", "trig", "n3", "jsonld"]	Languages SWLS is enabled for. Values: turtle, trig, n3, jsonld, sparql (experimental)
swls.formatLanguages	string[]	["turtle"]	Languages document formatting is enabled for. Values: turtle, trig, n3, jsonld
swls.checkUpdate	boolean	true	Check GitHub for new releases on startup
swls.automaticUpdate	boolean	false	Install updates without prompting
swls.log	string	"debug"	Log level: error, warn, info, debug, trace
swls.ontologies	string[]	[]	Extra ontology URLs to load
swls.shapes	string[]	[]	Extra SHACL shape URLs to load
swls.prefixDisabled	string[]	[]	Prefixes from prefix.cc to hide from completions
swls.completion.mode	string	"none"	Property completion mode: none (server default), loose (all properties), strict (domain-matched only)
swls.completion.exceptions	string[]	[]	Namespace IRIs that get the opposite treatment of completion.mode: forced strict in loose mode, always suggested in strict mode. Ignored when mode is none
swls.prefixFormat	string	"turtle"	Syntax for inserted Turtle/TriG prefix declarations: turtle (@prefix ex: <...> .) or sparql (PREFIX ex: <...>)
swls.disabled	string[]	[]	Features and diagnostics to turn off. Pick from the values below (in Settings UI: Add Item → choose from the dropdown)

swls.disabled values

Value	Disables
shapes	SHACL shape validation
undefined_prefix	The undeclared-prefix diagnostic
unused_prefix	The unused-prefix diagnostic
namespace_properties	The closed-namespace property diagnostic
syntax_diagnostics	Syntax/parse error diagnostics
completion	Completion entirely
completion_keyword	Keyword completion
completion_class	Class-name completion
completion_property	Property completion
completion_prefix	Prefix-name completion
completion_subject	Subject-IRI completion (Turtle only)
hover	Hover entirely
hover_type	Inferred-type hover
hover_class	Class documentation hover
hover_property	Property documentation hover
hover_excluded_property	Allow-listed-property hover explanation
goto_definition	Goto-definition entirely
goto_definition_components_js	Components.js goto-definition
goto_type_definition	Goto type-definition
references	Find-all-references
rename	Rename
semantic_tokens	Semantic tokens
format	Document formatting
prefix_auto_insert	Auto-inserting missing prefix declarations
code_action	Code actions entirely
code_action_organize_imports	The "Organize Imports" quick-fix
code_action_blank_node_refactor	Blank-node refactor quick-fixes
inlay_hint	Inlay hints

Deprecated but still honored, so existing configs keep working: the per-feature swls.disable.<name>, per-language swls.<lang> and swls.format.<lang> booleans, and swls.completion.strict / swls.completion.except (replaced by swls.completion.exceptions).

Documentation

• lsp-core
• lang-turtle
• lang-jsonld
• lang-sparql
• swls

Screenshots

Undefined prefix	Shape violation

Class completion	Property completion

Support

If SWLS helps your workflow, consider supporting development:

☕ https://ko-fi.com/ajuvercr