diff --git a/Cargo.lock b/Cargo.lock
index 56ef09769..8d21d48ce 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -431,6 +431,12 @@ dependencies = [
  "cxx-build",
 ]
 
+[[package]]
+name = "if_chain"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb56e1aa765b4b4f3aadfab769793b7087bb03a4ea4920644a6d238e2df5b9ed"
+
 [[package]]
 name = "image"
 version = "0.24.5"
@@ -1027,7 +1033,7 @@ dependencies = [
 [[package]]
 name = "symmie"
 version = "0.1.0"
-source = "git+https://github.com/typst/symmie#6280fb20455cb63e6886ba5bb35b95a4b376da68"
+source = "git+https://github.com/typst/symmie#8d620b9854964a261ec954d7d08bfddc9c282b7c"
 
 [[package]]
 name = "syn"
@@ -1136,6 +1142,7 @@ dependencies = [
  "bytemuck",
  "comemo",
  "flate2",
+ "if_chain",
  "image",
  "miniz_oxide 0.5.4",
  "once_cell",
@@ -1150,6 +1157,7 @@ dependencies = [
  "siphasher",
  "subsetter",
  "svg2pdf",
+ "symmie",
  "thin-vec",
  "tiny-skia",
  "ttf-parser 0.17.1",
diff --git a/Cargo.toml b/Cargo.toml
index f38fc9972..9b7f6860b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,6 +17,7 @@ bitflags = "1"
 bytemuck = "1"
 comemo = { git = "https://github.com/typst/comemo" }
 flate2 = "1"
+if_chain = "1"
 image = { version = "0.24", default-features = false, features = ["png", "jpeg", "gif"] }
 miniz_oxide = "0.5"
 once_cell = "1"
@@ -31,6 +32,7 @@ serde = { version = "1", features = ["derive"] }
 siphasher = "0.3"
 subsetter = "0.1"
 svg2pdf = "0.4"
+symmie = { git = "https://github.com/typst/symmie" }
 thin-vec = "0.2"
 tiny-skia = "0.6.2"
 ttf-parser = "0.17"
diff --git a/src/ide/complete.rs b/src/ide/complete.rs
new file mode 100644
index 000000000..7f312727a
--- /dev/null
+++ b/src/ide/complete.rs
@@ -0,0 +1,684 @@
+use if_chain::if_chain;
+
+use crate::model::Value;
+use crate::syntax::{LinkedNode, Source, SyntaxKind};
+use crate::util::{format_eco, EcoString};
+use crate::World;
+
+/// An autocompletion option.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Completion {
+    /// The kind of item this completes to.
+    pub kind: CompletionKind,
+    /// The label the completion is shown with.
+    pub label: EcoString,
+    /// The completed version of the input, defaults to the label.
+    ///
+    /// May use snippet syntax like `${lhs} + ${rhs}`.
+    pub apply: Option<EcoString>,
+    /// Details about the completed item.
+    pub detail: Option<EcoString>,
+}
+
+/// A kind of item that can be completed.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub enum CompletionKind {
+    /// A syntactical structure.
+    Syntax,
+    /// A function name.
+    Function,
+    /// A constant of the given type.
+    Constant,
+    /// A symbol.
+    Symbol,
+}
+
+/// Autocomplete a cursor position in a source file.
+///
+/// Returns the position from which the completions apply and a list of
+/// completions.
+///
+/// When `explicit` is `true`, the user requested the completion by pressing
+/// control and space or something similar.
+pub fn autocomplete(
+    world: &dyn World,
+    source: &Source,
+    cursor: usize,
+    explicit: bool,
+) -> Option<(usize, Vec<Completion>)> {
+    let mut ctx = CompletionContext::new(world, source, cursor, explicit)?;
+
+    let _ = complete_rules(&mut ctx)
+        || complete_symbols(&mut ctx)
+        || complete_markup(&mut ctx)
+        || complete_math(&mut ctx)
+        || complete_code(&mut ctx);
+
+    Some((ctx.from, ctx.completions))
+}
+
+/// Complete set and show rules.
+fn complete_rules(ctx: &mut CompletionContext) -> bool {
+    // We don't want to complete directly behind the keyword.
+    if !ctx.leaf.kind().is_trivia() {
+        return false;
+    }
+
+    let Some(prev) = ctx.leaf.prev_leaf() else { return false };
+
+    // Behind the set keyword: "set |".
+    if matches!(prev.kind(), SyntaxKind::Set) {
+        ctx.set_rule_completions(ctx.cursor);
+        return true;
+    }
+
+    // Behind the show keyword: "show |".
+    if matches!(prev.kind(), SyntaxKind::Show) {
+        ctx.show_rule_selector_completions(ctx.cursor);
+        return true;
+    }
+
+    // Behind a half-completed show rule: "show strong: |".
+    if_chain! {
+        if let Some(prev) = ctx.leaf.prev_leaf();
+        if matches!(prev.kind(), SyntaxKind::Colon);
+        if matches!(prev.parent_kind(), Some(SyntaxKind::ShowRule));
+        then {
+            ctx.show_rule_recipe_completions(ctx.cursor);
+            return true;
+        }
+    }
+
+    false
+}
+
+/// Complete symbols.
+///
+/// Exception: Math identifiers which can also be symbols are handled separately
+/// in `math_completions`.
+fn complete_symbols(ctx: &mut CompletionContext) -> bool {
+    // Whether a colon is necessary.
+    let needs_colon = !ctx.text[ctx.cursor..].starts_with(':');
+
+    // Behind half-completed symbol: "$arrow:|$".
+    if_chain! {
+        if matches!(ctx.leaf.kind(), SyntaxKind::Atom(s) if s == ":");
+        if let Some(prev) = ctx.leaf.prev_leaf();
+        if matches!(prev.kind(), SyntaxKind::Ident(_));
+        then {
+            ctx.symbol_completions(prev.offset(), false);
+            return true;
+        }
+    }
+
+    // Start of a symbol: ":|".
+    // Checking for a text node ensures that "\:" isn't completed.
+    if ctx.text[..ctx.cursor].ends_with(':')
+        && matches!(ctx.leaf.kind(), SyntaxKind::Text(_) | SyntaxKind::Atom(_))
+    {
+        ctx.symbol_completions(ctx.cursor, needs_colon);
+        return true;
+    }
+
+    // An existing symbol: ":arrow:".
+    if matches!(ctx.leaf.kind(), SyntaxKind::Symbol(_)) {
+        // We want to complete behind the colon, therefore plus 1.
+        let has_colon = ctx.text[ctx.leaf.offset()..].starts_with(':');
+        let from = ctx.leaf.offset() + (has_colon as usize);
+        ctx.symbol_completions(from, has_colon && needs_colon);
+        return true;
+    }
+
+    // Behind half-completed symbol: ":bar|" or ":arrow:dou|".
+    if_chain! {
+        if matches!(
+            ctx.leaf.kind(),
+            SyntaxKind::Text(_) | SyntaxKind::Atom(_) | SyntaxKind::Ident(_)
+        );
+        if let Some(prev) = ctx.leaf.prev_leaf();
+        if matches!(prev.kind(), SyntaxKind::Symbol(_)) || matches!(
+            prev.kind(),
+            SyntaxKind::Text(s) | SyntaxKind::Atom(s) if s == ":"
+        );
+        then {
+            // We want to complete behind the colon, therefore plus 1.
+            let from = prev.offset() + 1;
+            ctx.symbol_completions(from, needs_colon);
+            return true;
+        }
+    }
+
+    false
+}
+
+/// Complete in markup mode.
+fn complete_markup(ctx: &mut CompletionContext) -> bool {
+    // Bail if we aren't even in markup.
+    if !matches!(ctx.leaf.parent_kind(), None | Some(SyntaxKind::Markup { .. })) {
+        return false;
+    }
+
+    // Start of an interpolated identifier: "#|".
+    // Checking for a text node ensures that "\#" isn't completed.
+    if ctx.text[..ctx.cursor].ends_with('#')
+        && matches!(ctx.leaf.kind(), SyntaxKind::Text(_))
+    {
+        ctx.expr_completions(ctx.cursor, true);
+        return true;
+    }
+
+    // An existing identifier: "#pa|".
+    if matches!(ctx.leaf.kind(), SyntaxKind::Ident(_)) {
+        // We want to complete behind the hashtag, therefore plus 1.
+        let from = ctx.leaf.offset() + 1;
+        ctx.expr_completions(from, true);
+        return true;
+    }
+
+    // Behind a half-completed binding: "#let x = |".
+    if_chain! {
+        if let Some(prev) = ctx.leaf.prev_leaf();
+        if matches!(prev.kind(), SyntaxKind::Eq);
+        if matches!(prev.parent_kind(), Some(SyntaxKind::LetBinding));
+        then {
+            ctx.expr_completions(ctx.cursor, false);
+            return true;
+        }
+    }
+
+    // Anywhere: "|".
+    if ctx.explicit {
+        ctx.markup_completions(ctx.cursor);
+        return true;
+    }
+
+    false
+}
+
+/// Complete in math mode.
+fn complete_math(ctx: &mut CompletionContext) -> bool {
+    if !matches!(
+        ctx.leaf.parent_kind(),
+        Some(SyntaxKind::Math) | Some(SyntaxKind::Frac) | Some(SyntaxKind::Script)
+    ) {
+        return false;
+    }
+
+    // Start of an interpolated identifier: "#|".
+    if matches!(ctx.leaf.kind(), SyntaxKind::Atom(s) if s == "#") {
+        ctx.expr_completions(ctx.cursor, true);
+        return true;
+    }
+
+    // Behind existing atom or identifier: "$a|$" or "$abc|$".
+    if matches!(ctx.leaf.kind(), SyntaxKind::Atom(_) | SyntaxKind::Ident(_)) {
+        let from = ctx.leaf.offset();
+        ctx.symbol_completions(from, false);
+        ctx.scope_completions(from);
+        return true;
+    }
+
+    // Anywhere: "$|$".
+    if ctx.explicit {
+        ctx.math_completions(ctx.cursor);
+        return true;
+    }
+
+    false
+}
+
+/// Complete in code mode.
+fn complete_code(ctx: &mut CompletionContext) -> bool {
+    if matches!(
+        ctx.leaf.parent_kind(),
+        None | Some(SyntaxKind::Markup { .. }) | Some(SyntaxKind::Math)
+    ) {
+        return false;
+    }
+
+    // An existing identifier: "{ pa| }".
+    if matches!(ctx.leaf.kind(), SyntaxKind::Ident(_)) {
+        let from = ctx.leaf.offset();
+        ctx.expr_completions(from, true);
+        return true;
+    }
+
+    // Anywhere: "{ | }".
+    // But not within or after an expression.
+    if ctx.explicit
+        && (ctx.leaf.kind().is_trivia()
+            || matches!(ctx.leaf.kind(), SyntaxKind::LeftParen | SyntaxKind::LeftBrace))
+    {
+        ctx.expr_completions(ctx.cursor, false);
+        return true;
+    }
+
+    false
+}
+
+/// Context for autocompletion.
+struct CompletionContext<'a> {
+    world: &'a dyn World,
+    text: &'a str,
+    leaf: LinkedNode<'a>,
+    cursor: usize,
+    explicit: bool,
+    from: usize,
+    completions: Vec<Completion>,
+}
+
+impl<'a> CompletionContext<'a> {
+    /// Create a new autocompletion context.
+    fn new(
+        world: &'a dyn World,
+        source: &'a Source,
+        cursor: usize,
+        explicit: bool,
+    ) -> Option<Self> {
+        let leaf = LinkedNode::new(source.root()).leaf_at(cursor)?;
+        Some(Self {
+            world,
+            text: source.text(),
+            leaf,
+            cursor,
+            explicit,
+            from: cursor,
+            completions: vec![],
+        })
+    }
+
+    /// Add completions for all functions from the global scope.
+    fn set_rule_completions(&mut self, from: usize) {
+        self.scope_completions_where(
+            from,
+            |value| matches!(value, Value::Func(_)),
+            "(${})",
+        );
+    }
+
+    /// Add completions for selectors.
+    fn show_rule_selector_completions(&mut self, from: usize) {
+        self.snippet(
+            "text selector",
+            "\"${text}\": ${}",
+            "Replace occurances of specific text.",
+        );
+
+        self.snippet(
+            "regex selector",
+            "regex(\"${regex}\"): ${}",
+            "Replace matches of a regular expression.",
+        );
+
+        self.scope_completions_where(
+            from,
+            |value| matches!(value, Value::Func(func) if func.select(None).is_ok()),
+            ": ${}",
+        );
+    }
+
+    /// Add completions for selectors.
+    fn show_rule_recipe_completions(&mut self, from: usize) {
+        self.snippet(
+            "replacement",
+            "[${content}]",
+            "Replace the selected element with content.",
+        );
+
+        self.snippet(
+            "replacement (string)",
+            "\"${text}\"",
+            "Replace the selected element with a string of text.",
+        );
+
+        self.snippet(
+            "transformation",
+            "element => [${content}]",
+            "Transform the element with a function.",
+        );
+
+        self.scope_completions_where(from, |value| matches!(value, Value::Func(_)), "");
+    }
+
+    /// Add completions for the global scope.
+    fn scope_completions(&mut self, from: usize) {
+        self.scope_completions_where(from, |_| true, "");
+    }
+
+    /// Add completions for a subset of the global scope.
+    fn scope_completions_where(
+        &mut self,
+        from: usize,
+        filter: fn(&Value) -> bool,
+        extra: &str,
+    ) {
+        self.from = from;
+        for (name, value) in self.world.library().scope.iter() {
+            if filter(value) {
+                let apply = (!extra.is_empty()).then(|| format_eco!("{name}{extra}"));
+                self.completions.push(match value {
+                    Value::Func(func) => Completion {
+                        kind: CompletionKind::Function,
+                        label: name.clone(),
+                        apply,
+                        detail: func.doc().map(Into::into),
+                    },
+                    v => Completion {
+                        kind: CompletionKind::Constant,
+                        label: name.clone(),
+                        apply,
+                        detail: Some(format_eco!(
+                            "Constant of type `{}`.",
+                            v.type_name()
+                        )),
+                    },
+                });
+            }
+        }
+    }
+
+    /// Add completions for all symbols.
+    fn symbol_completions(&mut self, from: usize, colon: bool) {
+        self.from = from;
+        self.completions.reserve(symmie::list().len());
+        for &(name, c) in symmie::list() {
+            self.completions.push(Completion {
+                kind: CompletionKind::Symbol,
+                label: name.into(),
+                apply: colon.then(|| format_eco!("{name}:")),
+                detail: Some(c.into()),
+            });
+        }
+    }
+
+    /// Add completions for markup snippets.
+    #[rustfmt::skip]
+    fn markup_completions(&mut self, from: usize) {
+        self.from = from;
+
+        self.snippet(
+            "linebreak",
+            "\\\n${}",
+            "Inserts a forced linebreak.",
+        );
+
+        self.snippet(
+            "symbol",
+            ":${}:",
+            "Inserts a symbol.",
+        );
+
+        self.snippet(
+            "strong text",
+            "*${strong}*",
+            "Strongly emphasizes content by increasing the font weight.",
+        );
+
+        self.snippet(
+            "emphasized text",
+            "_${emphasized}_",
+            "Emphasizes content by setting it in italic font style.",
+        );
+
+        self.snippet(
+            "raw text",
+            "`${text}`",
+            "Displays text verbatim, in monospace.",
+        );
+
+        self.snippet(
+            "code listing",
+            "```${lang}\n${code}\n```",
+            "Inserts computer code with syntax highlighting.",
+        );
+
+        self.snippet(
+            "hyperlink",
+            "https://${example.com}",
+            "Links to a URL.",
+        );
+
+        self.snippet(
+            "math (inline)",
+            "$${x}$",
+            "Inserts an inline-level mathematical formula.",
+        );
+
+        self.snippet(
+            "math (block)",
+            "$ ${sum_x^2} $",
+            "Inserts a block-level mathematical formula.",
+        );
+
+        self.snippet(
+            "label",
+            "<${name}>",
+            "Makes the preceding element referencable.",
+        );
+
+        self.snippet(
+            "reference",
+            "@${name}",
+            "Inserts a reference to a label.",
+        );
+
+        self.snippet(
+            "heading",
+            "= ${title}",
+            "Inserts a section heading.",
+        );
+
+        self.snippet(
+            "list item",
+            "- ${item}",
+            "Inserts an item of an unordered list.",
+        );
+
+        self.snippet(
+            "enumeration item",
+            "+ ${item}",
+            "Inserts an item of an ordered list.",
+        );
+
+        self.snippet(
+            "enumeration item (numbered)",
+            "${number}. ${item}",
+            "Inserts an explicitly numbered item of an ordered list.",
+        );
+
+        self.snippet(
+            "description list item",
+            "/ ${term}: ${description}",
+            "Inserts an item of a description list.",
+        );
+
+        self.snippet(
+            "expression",
+            "#${}",
+            "Variables, function calls, and more.",
+        );
+
+        self.snippet(
+            "code block",
+            "{ ${} }",
+            "Switches into code mode.",
+        );
+
+        self.snippet(
+            "content block",
+            "[${content}]",
+            "Inserts a nested content block that isolates styles.",
+        );
+    }
+
+    /// Add completions for math snippets.
+    #[rustfmt::skip]
+    fn math_completions(&mut self, from: usize) {
+        self.symbol_completions(from, false);
+        self.scope_completions(from);
+
+        self.snippet(
+            "subscript",
+            "${x}_${2:2}",
+            "Sets something in subscript.",
+        );
+
+        self.snippet(
+            "superscript",
+            "${x}^${2:2}",
+            "Sets something in superscript.",
+        );
+
+        self.snippet(
+            "fraction",
+            "${x}/${y}",
+            "Inserts a fraction.",
+        );
+    }
+
+    /// Add completions for expression snippets.
+    #[rustfmt::skip]
+    fn expr_completions(&mut self, from: usize, short_form: bool) {
+        self.scope_completions(from);
+
+        self.snippet(
+            "variable",
+            "${variable}",
+            "Accesses a variable.",
+        );
+
+        self.snippet(
+            "function call",
+            "${function}(${arguments})[${body}]",
+            "Evaluates a function.",
+        );
+
+        self.snippet(
+            "set rule",
+            "set ${}",
+            "Sets style properties on an element.",
+        );
+
+        self.snippet(
+            "show rule",
+            "show ${}",
+            "Redefines the look of an element.",
+        );
+
+        self.snippet(
+            "let binding",
+            "let ${name} = ${value}",
+            "Saves a value in a variable.",
+        );
+
+        self.snippet(
+            "let binding (function)",
+            "let ${name}(${params}) = ${output}",
+            "Defines a function.",
+        );
+
+        self.snippet(
+            "if conditional",
+            "if ${1 < 2} {\n\t${}\n}",
+            "Computes or inserts something conditionally.",
+        );
+
+        self.snippet(
+            "if-else conditional",
+            "if ${1 < 2} {\n\t${}\n} else {\n\t${}\n}",
+            "Computes or inserts different things based on a condition.",
+        );
+
+        self.snippet(
+            "while loop",
+            "while ${1 < 2} {\n\t${}\n}",
+            "Computes or inserts somthing while a condition is met.",
+        );
+
+        self.snippet(
+            "for loop",
+            "for ${value} in ${(1, 2, 3)} {\n\t${}\n}",
+            "Computes or inserts somthing for each value in a collection.",
+        );
+
+        self.snippet(
+            "for loop (with key)",
+            "for ${key}, ${value} in ${(a: 1, b: 2)} {\n\t${}\n}",
+            "Computes or inserts somthing for each key and value in a collection.",
+        );
+
+        self.snippet(
+            "break",
+            "break",
+            "Exits early from a loop.",
+        );
+
+        self.snippet(
+            "continue",
+            "continue",
+            "Continues with the next iteration of a loop.",
+        );
+
+        self.snippet(
+            "return",
+            "return ${output}",
+            "Returns early from a function.",
+        );
+
+        self.snippet(
+            "import",
+            "import ${items} from \"${file.typ}\"",
+            "Imports variables from another file.",
+        );
+
+        self.snippet(
+            "include",
+            "include \"${file.typ}\"",
+            "Includes content from another file.",
+        );
+
+        if short_form {
+            return;
+        }
+
+        self.snippet(
+            "code block",
+            "{ ${} }",
+            "Inserts a nested code block.",
+        );
+
+        self.snippet(
+            "content block",
+            "[${content}]",
+            "Switches into markup mode.",
+        );
+
+        self.snippet(
+            "array",
+            "(${1, 2, 3})",
+            "Creates a sequence of values.",
+        );
+
+        self.snippet(
+            "dictionary",
+            "(${a: 1, b: 2})",
+            "Creates a mapping from names to value.",
+        );
+
+        self.snippet(
+            "anonymous function",
+            "(${params}) => ${output}",
+            "Creates an unnamed function.",
+        );
+    }
+
+    /// Add a snippet completion.
+    fn snippet(&mut self, label: &str, snippet: &str, detail: &str) {
+        self.completions.push(Completion {
+            kind: CompletionKind::Syntax,
+            label: label.into(),
+            apply: Some(snippet.into()),
+            detail: Some(detail.into()),
+        });
+    }
+}
diff --git a/src/ide/mod.rs b/src/ide/mod.rs
index a44279836..8068d4213 100644
--- a/src/ide/mod.rs
+++ b/src/ide/mod.rs
@@ -1,7 +1,9 @@
 //! Capabilities for IDE support.
 
+mod complete;
 mod highlight;
 mod tooltip;
 
+pub use complete::*;
 pub use highlight::*;
 pub use tooltip::*;