diff --git a/crates/decodal-cli/src/main.rs b/crates/decodal-cli/src/main.rs
index 525868e..f040243 100644
--- a/crates/decodal-cli/src/main.rs
+++ b/crates/decodal-cli/src/main.rs
@@ -6,7 +6,7 @@ use std::{
 
 use decodal::{
     Data, Diagnostic, DiagnosticKind, Engine, LoadedSource, SourceId, SourceLoader, Span,
-    format_diagnostic_with, format_source_with_source_id,
+    format_diagnostic_with,
 };
 
 fn main() -> ExitCode {
@@ -38,17 +38,6 @@ fn run() -> Result<(), String> {
             println!("ok");
             Ok(())
         }
-        "fmt" | "format" => {
-            let next = args.next().unwrap_or_else(|| String::from("-"));
-            if next == "--write" || next == "-w" {
-                let path = args
-                    .next()
-                    .ok_or_else(|| String::from("missing file path for `decodal fmt --write`"))?;
-                format_path(&path, true)
-            } else {
-                format_path(&next, false)
-            }
-        }
         "eval" | "materialize" => {
             let path = args.next().unwrap_or_else(|| String::from("-"));
             let data = materialize_path(&path)?;
@@ -65,21 +54,6 @@ fn run() -> Result<(), String> {
     }
 }
 
-fn format_path(path: &str, write: bool) -> Result<(), String> {
-    if write && path == "-" {
-        return Err(String::from("cannot use --write with stdin"));
-    }
-    let root = read_root_source(path).map_err(format_raw_diagnostic)?;
-    let formatted = format_source_with_source_id(SourceId(0), &root.source)
-        .map_err(|error| format_diagnostic_with_root(&error, &root.name))?;
-    if write {
-        fs::write(path, formatted).map_err(|error| format!("failed to write `{path}`: {error}"))?;
-    } else {
-        print!("{formatted}");
-    }
-    Ok(())
-}
-
 fn materialize_path(path: &str) -> Result<Data, String> {
     let root = read_root_source(path).map_err(format_raw_diagnostic)?;
     let root_name = root.name.clone();
@@ -169,11 +143,10 @@ fn print_help() {
     println!("Decodal - Deferred Constraint Data Language");
     println!();
     println!("Usage:");
-    println!("  decodal <file.dcdl>             Materialize a DCDL file");
-    println!("  decodal eval <file.dcdl>        Materialize a DCDL file");
-    println!("  decodal check <file.dcdl>       Evaluate and materialize without printing data");
-    println!("  decodal fmt [--write] <file.dcdl> Format a DCDL file");
-    println!("  decodal -                       Read DCDL source from stdin");
+    println!("  decodal <file.dcdl>        Materialize a DCDL file");
+    println!("  decodal eval <file.dcdl>   Materialize a DCDL file");
+    println!("  decodal check <file.dcdl>  Evaluate and materialize without printing data");
+    println!("  decodal -                  Read DCDL source from stdin");
 }
 
 fn format_diagnostic_with_root(error: &Diagnostic, root_name: &str) -> String {
diff --git a/crates/decodal-core/src/formatter.rs b/crates/decodal-core/src/formatter.rs
deleted file mode 100644
index 321d5d1..0000000
--- a/crates/decodal-core/src/formatter.rs
+++ /dev/null
@@ -1,442 +0,0 @@
-use alloc::string::{String, ToString};
-use core::fmt::Write;
-
-use crate::{
-    Ast, Diagnostic, Expr, ExprId, Field, Literal, Param, SourceForm, Span,
-    ast::{BinaryOp, CompareOp, MatchArm, UnaryOp},
-    diagnostic::Result,
-    parse_source_with_source_id,
-    span::SourceId,
-};
-
-const INDENT: usize = 4;
-
-pub fn format_source(source: &str) -> Result<String> {
-    format_source_with_source_id(SourceId(0), source)
-}
-
-pub fn format_source_with_source_id(source_id: SourceId, source: &str) -> Result<String> {
-    reject_comments(source_id, source)?;
-    let parsed = parse_source_with_source_id(source_id, source)?;
-    Ok(Formatter::new(&parsed.ast).format_root(parsed.root, parsed.source_form))
-}
-
-struct Formatter<'a> {
-    ast: &'a Ast,
-}
-
-impl<'a> Formatter<'a> {
-    fn new(ast: &'a Ast) -> Self {
-        Self { ast }
-    }
-
-    fn format_root(&self, root: ExprId, source_form: SourceForm) -> String {
-        let mut out = String::new();
-        match source_form {
-            SourceForm::Fields => {
-                if let Expr::Object(fields) = &self.ast.get(root).expr {
-                    self.write_fields(&mut out, fields, 0);
-                } else {
-                    self.write_expr(&mut out, root, 0, 0);
-                }
-            }
-            SourceForm::Expr => self.write_expr(&mut out, root, 0, 0),
-        }
-        if !out.ends_with('\n') {
-            out.push('\n');
-        }
-        out
-    }
-
-    fn write_expr(&self, out: &mut String, id: ExprId, indent: usize, parent_prec: u8) {
-        let expr = &self.ast.get(id).expr;
-        let prec = expr_prec(expr);
-        let paren = prec < parent_prec;
-        if paren {
-            out.push('(');
-        }
-        match expr {
-            Expr::Literal(literal) => self.write_literal(out, literal),
-            Expr::Ident(name) => out.push_str(name),
-            Expr::Object(fields) => self.write_object(out, fields, indent),
-            Expr::Array(items) => self.write_array(out, items, indent),
-            Expr::Let { bindings, body } => self.write_let(out, bindings, *body, indent),
-            Expr::Import(path) => {
-                out.push_str("import ");
-                write_quoted(out, path);
-            }
-            Expr::Path { base, field } => {
-                self.write_expr(out, *base, indent, prec);
-                out.push('.');
-                out.push_str(field);
-            }
-            Expr::Call { callee, args } => {
-                self.write_expr(out, *callee, indent, prec);
-                out.push('(');
-                for (index, arg) in args.iter().enumerate() {
-                    if index > 0 {
-                        out.push_str(", ");
-                    }
-                    self.write_expr(out, *arg, indent, 0);
-                }
-                out.push(')');
-            }
-            Expr::Function { params, body } => self.write_function(out, params, *body, indent),
-            Expr::Match { scrutinee, arms } => self.write_match(out, *scrutinee, arms, indent),
-            Expr::Unary { op, expr } => {
-                out.push_str(match op {
-                    UnaryOp::Neg => "-",
-                    UnaryOp::Not => "!",
-                });
-                self.write_expr(out, *expr, indent, prec);
-            }
-            Expr::Binary { op, lhs, rhs } => {
-                self.write_expr(out, *lhs, indent, prec);
-                out.push(' ');
-                out.push_str(binary_op_text(*op));
-                out.push(' ');
-                self.write_expr(out, *rhs, indent, prec + 1);
-            }
-            Expr::Default { base, fallback } => {
-                self.write_expr(out, *base, indent, prec);
-                out.push_str(" default ");
-                self.write_expr(out, *fallback, indent, prec + 1);
-            }
-            Expr::CompareConstraint { op, value } => {
-                out.push_str(compare_op_text(*op));
-                out.push(' ');
-                self.write_expr(out, *value, indent, prec);
-            }
-            Expr::RegexConstraint(pattern) => {
-                out.push('/');
-                out.push_str(pattern);
-                out.push('/');
-            }
-            Expr::Wildcard => out.push('_'),
-        }
-        if paren {
-            out.push(')');
-        }
-    }
-
-    fn write_literal(&self, out: &mut String, literal: &Literal) {
-        match literal {
-            Literal::String(value) => write_quoted(out, value),
-            Literal::Int(value) => {
-                let _ = write!(out, "{value}");
-            }
-            Literal::Float(value) => {
-                let text = value.to_string();
-                out.push_str(&text);
-                if !text.contains('.') && !text.contains('e') && !text.contains('E') {
-                    out.push_str(".0");
-                }
-            }
-            Literal::Bool(value) => out.push_str(if *value { "true" } else { "false" }),
-        }
-    }
-
-    fn write_object(&self, out: &mut String, fields: &[Field], indent: usize) {
-        if fields.is_empty() {
-            out.push_str("{}");
-            return;
-        }
-        out.push('{');
-        out.push('\n');
-        self.write_fields(out, fields, indent + INDENT);
-        write_indent(out, indent);
-        out.push('}');
-    }
-
-    fn write_fields(&self, out: &mut String, fields: &[Field], indent: usize) {
-        for field in fields {
-            write_indent(out, indent);
-            self.write_field(out, field, indent);
-            out.push_str(";\n");
-        }
-    }
-
-    fn write_field(&self, out: &mut String, field: &Field, indent: usize) {
-        for (index, part) in field.path.iter().enumerate() {
-            if index > 0 {
-                out.push('.');
-            }
-            out.push_str(part);
-        }
-        out.push_str(" = ");
-        self.write_expr(out, field.value, indent, 0);
-    }
-
-    fn write_array(&self, out: &mut String, items: &[ExprId], indent: usize) {
-        if items.is_empty() {
-            out.push_str("[]");
-            return;
-        }
-        if items.iter().all(|item| self.is_inline(*item)) {
-            out.push('[');
-            for (index, item) in items.iter().enumerate() {
-                if index > 0 {
-                    out.push_str(", ");
-                }
-                self.write_expr(out, *item, indent, 0);
-            }
-            out.push(']');
-            return;
-        }
-        out.push('[');
-        out.push('\n');
-        for item in items {
-            write_indent(out, indent + INDENT);
-            self.write_expr(out, *item, indent + INDENT, 0);
-            out.push_str(",\n");
-        }
-        write_indent(out, indent);
-        out.push(']');
-    }
-
-    fn write_let(&self, out: &mut String, bindings: &[Field], body: ExprId, indent: usize) {
-        out.push_str("let");
-        out.push('\n');
-        self.write_fields(out, bindings, indent + INDENT);
-        write_indent(out, indent);
-        out.push_str("in");
-        out.push('\n');
-        write_indent(out, indent + INDENT);
-        self.write_expr(out, body, indent + INDENT, 0);
-    }
-
-    fn write_function(&self, out: &mut String, params: &[Param], body: ExprId, indent: usize) {
-        out.push('(');
-        for (index, param) in params.iter().enumerate() {
-            if index > 0 {
-                out.push_str(", ");
-            }
-            self.write_param(out, param, indent);
-        }
-        out.push(')');
-        out.push_str(" =>");
-        if self.is_inline(body) {
-            out.push(' ');
-            self.write_expr(out, body, indent, 0);
-        } else {
-            out.push('\n');
-            write_indent(out, indent + INDENT);
-            self.write_expr(out, body, indent + INDENT, 0);
-        }
-    }
-
-    fn write_param(&self, out: &mut String, param: &Param, indent: usize) {
-        out.push_str(&param.name);
-        if let Some(constraint) = param.constraint {
-            out.push_str(": ");
-            self.write_expr(out, constraint, indent, 0);
-        }
-    }
-
-    fn write_match(&self, out: &mut String, scrutinee: ExprId, arms: &[MatchArm], indent: usize) {
-        out.push_str("match ");
-        self.write_expr(out, scrutinee, indent, 0);
-        out.push_str(" {");
-        if !arms.is_empty() {
-            out.push('\n');
-            for arm in arms {
-                write_indent(out, indent + INDENT);
-                self.write_expr(out, arm.pattern, indent + INDENT, 0);
-                out.push_str(": ");
-                self.write_expr(out, arm.body, indent + INDENT, 0);
-                out.push_str(";\n");
-            }
-            write_indent(out, indent);
-        }
-        out.push('}');
-    }
-
-    fn is_inline(&self, id: ExprId) -> bool {
-        match &self.ast.get(id).expr {
-            Expr::Literal(_)
-            | Expr::Ident(_)
-            | Expr::Import(_)
-            | Expr::RegexConstraint(_)
-            | Expr::Wildcard => true,
-            Expr::Path { base, .. } => self.is_inline(*base),
-            Expr::Call { callee, args } => {
-                self.is_inline(*callee) && args.iter().all(|arg| self.is_inline(*arg))
-            }
-            Expr::Unary { expr, .. } => self.is_inline(*expr),
-            Expr::Binary { lhs, rhs, .. } => self.is_inline(*lhs) && self.is_inline(*rhs),
-            Expr::Default { base, fallback } => self.is_inline(*base) && self.is_inline(*fallback),
-            Expr::CompareConstraint { value, .. } => self.is_inline(*value),
-            Expr::Array(items) => items.iter().all(|item| self.is_inline(*item)),
-            Expr::Object(fields) => fields.is_empty(),
-            Expr::Let { .. } | Expr::Function { .. } | Expr::Match { .. } => false,
-        }
-    }
-}
-
-fn expr_prec(expr: &Expr) -> u8 {
-    match expr {
-        Expr::Default { .. } => 1,
-        Expr::Binary { op, .. } => binary_prec(*op),
-        Expr::Unary { .. } | Expr::CompareConstraint { .. } => 17,
-        Expr::Path { .. } | Expr::Call { .. } => 19,
-        _ => 20,
-    }
-}
-
-fn binary_prec(op: BinaryOp) -> u8 {
-    match op {
-        BinaryOp::Patch => 3,
-        BinaryOp::And => 5,
-        BinaryOp::LogicalOr => 7,
-        BinaryOp::LogicalAnd => 9,
-        BinaryOp::Equal
-        | BinaryOp::NotEqual
-        | BinaryOp::Greater
-        | BinaryOp::GreaterEqual
-        | BinaryOp::Less
-        | BinaryOp::LessEqual => 11,
-        BinaryOp::Concat => 12,
-        BinaryOp::Add | BinaryOp::Sub => 13,
-        BinaryOp::Mul | BinaryOp::Div => 15,
-    }
-}
-
-fn binary_op_text(op: BinaryOp) -> &'static str {
-    match op {
-        BinaryOp::Add => "+",
-        BinaryOp::Sub => "-",
-        BinaryOp::Mul => "*",
-        BinaryOp::Div => "/",
-        BinaryOp::Concat => "++",
-        BinaryOp::Equal => "==",
-        BinaryOp::NotEqual => "!=",
-        BinaryOp::Greater => ">",
-        BinaryOp::GreaterEqual => ">=",
-        BinaryOp::Less => "<",
-        BinaryOp::LessEqual => "<=",
-        BinaryOp::LogicalAnd => "&&",
-        BinaryOp::LogicalOr => "||",
-        BinaryOp::And => "&",
-        BinaryOp::Patch => "//",
-    }
-}
-
-fn compare_op_text(op: CompareOp) -> &'static str {
-    match op {
-        CompareOp::Gt => ">",
-        CompareOp::Gte => ">=",
-        CompareOp::Lt => "<",
-        CompareOp::Lte => "<=",
-        CompareOp::Eq => "==",
-    }
-}
-
-fn write_indent(out: &mut String, indent: usize) {
-    for _ in 0..indent {
-        out.push(' ');
-    }
-}
-
-fn write_quoted(out: &mut String, value: &str) {
-    out.push('"');
-    for ch in value.chars() {
-        match ch {
-            '"' => out.push_str("\\\""),
-            '\\' => out.push_str("\\\\"),
-            '\n' => out.push_str("\\n"),
-            '\r' => out.push_str("\\r"),
-            '\t' => out.push_str("\\t"),
-            ch if ch.is_control() => {
-                let _ = write!(out, "\\u{:04x}", ch as u32);
-            }
-            ch => out.push(ch),
-        }
-    }
-    out.push('"');
-}
-
-fn reject_comments(source_id: SourceId, source: &str) -> Result<()> {
-    if let Some(offset) = comment_offset(source) {
-        return Err(Diagnostic::syntax(
-            Span::new(source_id, offset, offset + 1),
-            "formatter does not yet preserve comments",
-        ));
-    }
-    Ok(())
-}
-
-fn comment_offset(source: &str) -> Option<usize> {
-    let bytes = source.as_bytes();
-    let mut index = 0;
-    while index < bytes.len() {
-        match bytes[index] {
-            b'"' => {
-                index += 1;
-                while index < bytes.len() {
-                    match bytes[index] {
-                        b'\\' => index += 2,
-                        b'"' => {
-                            index += 1;
-                            break;
-                        }
-                        _ => index += 1,
-                    }
-                }
-            }
-            b'#' => return Some(index),
-            _ => index += 1,
-        }
-    }
-    None
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::parse_source;
-
-    #[test]
-    fn formats_top_level_fields() {
-        let formatted = format_source("port=Int&>=1 default 8080;name=String;").unwrap();
-        assert_eq!(
-            formatted,
-            "port = Int & >= 1 default 8080;\nname = String;\n"
-        );
-        parse_source(&formatted).unwrap();
-    }
-
-    #[test]
-    fn formats_nested_objects() {
-        let formatted =
-            format_source("Server={host=String default \"localhost\";port=Int&>0;};").unwrap();
-        assert_eq!(
-            formatted,
-            "Server = {\n    host = String default \"localhost\";\n    port = Int & > 0;\n};\n"
-        );
-        parse_source(&formatted).unwrap();
-    }
-
-    #[test]
-    fn formats_let_function_match_and_array() {
-        let source = "let f=(x:Int)=>match x{_: [1,{a=2;}];};in f(1)";
-        let formatted = format_source(source).unwrap();
-        assert_eq!(
-            formatted,
-            "let\n    f = (x: Int) =>\n        match x {\n            _: [\n                1,\n                {\n                    a = 2;\n                },\n            ];\n        };\nin\n    f(1)\n"
-        );
-        parse_source(&formatted).unwrap();
-    }
-
-    #[test]
-    fn preserves_needed_parentheses() {
-        let formatted = format_source("value=(1+2)*3;").unwrap();
-        assert_eq!(formatted, "value = (1 + 2) * 3;\n");
-        parse_source(&formatted).unwrap();
-    }
-
-    #[test]
-    fn rejects_comments_instead_of_dropping_them() {
-        let error = format_source("# keep me\nvalue = 1;").unwrap_err();
-        assert_eq!(error.message, "formatter does not yet preserve comments");
-    }
-}
diff --git a/crates/decodal-core/src/lib.rs b/crates/decodal-core/src/lib.rs
index ce16e85..27900be 100644
--- a/crates/decodal-core/src/lib.rs
+++ b/crates/decodal-core/src/lib.rs
@@ -7,7 +7,6 @@ pub mod constraints;
 pub mod diagnostic;
 pub mod embedding;
 pub mod eval;
-pub mod formatter;
 mod lexer;
 pub mod module;
 pub mod parser;
@@ -22,7 +21,6 @@ pub use decodal_derive::Decodal;
 pub use diagnostic::{Diagnostic, DiagnosticKind, Result};
 pub use embedding::{HostField, HostValue};
 pub use eval::{Engine, format_diagnostic_with};
-pub use formatter::{format_source, format_source_with_source_id};
 pub use module::{EmptyLoader, LoadedSource, Module, SourceLoader};
 pub use parser::{ParseOutput, Parser, SourceForm, parse_source, parse_source_with_source_id};
 pub use runtime::{Constraint, Data, ExprRef, LiteralValue, ModuleId, PrimitiveType, RuntimeValue};
diff --git a/crates/decodal-wasm/src/lib.rs b/crates/decodal-wasm/src/lib.rs
index 31df9ab..1c5f7af 100644
--- a/crates/decodal-wasm/src/lib.rs
+++ b/crates/decodal-wasm/src/lib.rs
@@ -2,7 +2,7 @@ use std::collections::BTreeMap;
 
 use decodal::{
     Data, Diagnostic, DiagnosticKind, EmptyLoader, Engine, LoadedSource, SourceId, SourceLoader,
-    Span, format_diagnostic_with, format_source,
+    Span, format_diagnostic_with,
 };
 use wasm_bindgen::prelude::*;
 
@@ -11,17 +11,6 @@ pub fn evaluate(source: &str) -> String {
     encode_result(evaluate_inner(source))
 }
 
-#[wasm_bindgen(js_name = formatSource)]
-pub fn format_source_json(source: &str) -> String {
-    match format_source(source) {
-        Ok(formatted) => format!("{{\"ok\":true,\"source\":{}}}", json_string(&formatted)),
-        Err(error) => format!(
-            "{{\"ok\":false,\"error\":{}}}",
-            json_string(&format_diagnostic_with_root(&error, "playground"))
-        ),
-    }
-}
-
 #[wasm_bindgen(js_name = evaluateProject)]
 pub fn evaluate_project(entry: &str, files_json: &str) -> String {
     encode_result(evaluate_project_inner(entry, files_json))
@@ -225,13 +214,6 @@ fn json_string(value: &str) -> String {
 mod tests {
     use super::{evaluate_project_inner, normalize_path, resolve_import};
 
-    #[test]
-    fn formats_source_for_web() {
-        let output = super::format_source_json("value={a=1;};");
-        assert!(output.contains("\"ok\":true"));
-        assert!(output.contains("value = {\\n    a = 1;\\n};\\n"));
-    }
-
     #[test]
     fn normalizes_virtual_paths() {
         assert_eq!(
diff --git a/doc/manual/souce/components.md b/doc/manual/souce/components.md
index c1f5a9c..83f50b3 100644
--- a/doc/manual/souce/components.md
+++ b/doc/manual/souce/components.md
@@ -8,7 +8,7 @@ The public surface is intentionally organized by use case: execute Decodal with
 ### Rust crate
 
 The `decodal` crate is the primary Rust runtime and embedding API.
-It owns parsing, formatting, evaluation, materialization, diagnostics, host-provided values, and schema/decode traits.
+It owns parsing, evaluation, materialization, diagnostics, host-provided values, and schema/decode traits.
 Rust applications should use this crate when they want to load Decodal source, evaluate it, or embed Decodal into a host program.
 
 Important paths:
diff --git a/doc/manual/souce/formatting.md b/doc/manual/souce/formatting.md
deleted file mode 100644
index 623e4ac..0000000
--- a/doc/manual/souce/formatting.md
+++ /dev/null
@@ -1,50 +0,0 @@
-# Formatting
-
-Decodal includes an initial source formatter for parsed Decodal code.
-The formatter is available from the Rust crate, the CLI, the WebAssembly package, and the playground.
-
-## CLI
-
-Print formatted source to stdout:
-
-```sh
-decodal fmt config.dcdl
-```
-
-Format in place:
-
-```sh
-decodal fmt --write config.dcdl
-```
-
-Read from stdin:
-
-```sh
-cat config.dcdl | decodal fmt -
-```
-
-## Rust
-
-```rust
-let formatted = decodal::format_source("Server={port=Int default 8080;};")?;
-```
-
-## WebAssembly
-
-```js
-import init, { formatSource } from 'decodal-wasm';
-
-await init();
-const result = JSON.parse(formatSource('Server={port=Int default 8080;};'));
-
-if (result.ok) {
-  console.log(result.source);
-} else {
-  console.error(result.error);
-}
-```
-
-## Current limitation
-
-The formatter currently rejects source containing line comments rather than silently dropping them.
-Comment-preserving formatting requires attaching comments to syntax nodes or formatting from a concrete syntax tree, and should be implemented before comment-heavy source is formatted automatically.
diff --git a/doc/manual/souce/index.md b/doc/manual/souce/index.md
index d17bc4d..b4a1323 100644
--- a/doc/manual/souce/index.md
+++ b/doc/manual/souce/index.md
@@ -7,8 +7,7 @@ Decodal は Deferred Constraint Data Language、略称 DCDL のプロジェク
 
 1. [Introduction](./introduction.md)
 2. [Components](./components.md)
-3. [Formatting](./formatting.md)
-4. [Language Specification](./language/index.md)
+3. [Language Specification](./language/index.md)
    1. [Lexical Structure and Syntax](./language/syntax.md)
    2. [Value](./language/value/index.md)
       1. [String](./language/value/string.md)
@@ -37,7 +36,7 @@ Decodal は Deferred Constraint Data Language、略称 DCDL のプロジェク
    9. [Materialization and Errors](./language/materialization-and-errors.md)
    10. [Naming Conventions](./language/naming.md)
    11. [Examples](./language/examples.md)
-5. [Implementation Design](./design/index.md)
+4. [Implementation Design](./design/index.md)
    1. [Execution Pipeline](./design/execution-pipeline.md)
    2. [Runtime Model](./design/runtime-model.md)
    3. [Thunk and Lazy Evaluation](./design/thunk-and-lazy-evaluation.md)
@@ -45,5 +44,5 @@ Decodal は Deferred Constraint Data Language、略称 DCDL のプロジェク
    5. [Diagnostics and Fallback](./design/diagnostics-and-fallback.md)
    6. [Embedding API](./design/embedding-api.md)
    7. [Features](./design/features.md)
-6. [Development](./development.md)
-7. [Open Issues](./open-issues.md)
+5. [Development](./development.md)
+6. [Open Issues](./open-issues.md)
diff --git a/packages/decodal-wasm/README.md b/packages/decodal-wasm/README.md
index 72cb7b2..7a33125 100644
--- a/packages/decodal-wasm/README.md
+++ b/packages/decodal-wasm/README.md
@@ -22,15 +22,15 @@ deno add jsr:@hare/decodal-wasm
 ## Usage
 
 ```js
-import init, { evaluateProject, formatSource } from 'decodal-wasm';
+import init, { evaluateProject } from 'decodal-wasm';
 
 await init();
 
-const formatted = JSON.parse(formatSource('Server={port=Int default 8080;};'));
-console.log(formatted.source);
-
-const result = evaluateProject('main.dcdl', JSON.stringify({
-  'main.dcdl': 'Server = { port = Int default 8080; };',
+const result = evaluateProject(JSON.stringify({
+  entry: 'main.dcdl',
+  files: {
+    'main.dcdl': 'Server = { port = Int default 8080; };',
+  },
 }));
 
 console.log(JSON.parse(result));
diff --git a/packages/decodal-wasm/decodal_wasm.d.ts b/packages/decodal-wasm/decodal_wasm.d.ts
index e56f72d..e88b72f 100644
--- a/packages/decodal-wasm/decodal_wasm.d.ts
+++ b/packages/decodal-wasm/decodal_wasm.d.ts
@@ -5,15 +5,12 @@ export function evaluate(source: string): string;
 
 export function evaluateProject(entry: string, files_json: string): string;
 
-export function formatSource(source: string): string;
-
 export type InitInput = RequestInfo | URL | Response | BufferSource | WebAssembly.Module;
 
 export interface InitOutput {
     readonly memory: WebAssembly.Memory;
     readonly evaluate: (a: number, b: number) => [number, number];
     readonly evaluateProject: (a: number, b: number, c: number, d: number) => [number, number];
-    readonly formatSource: (a: number, b: number) => [number, number];
     readonly __wbindgen_externrefs: WebAssembly.Table;
     readonly __wbindgen_malloc: (a: number, b: number) => number;
     readonly __wbindgen_realloc: (a: number, b: number, c: number, d: number) => number;
diff --git a/packages/decodal-wasm/decodal_wasm.js b/packages/decodal-wasm/decodal_wasm.js
index fe597bd..800a76f 100644
--- a/packages/decodal-wasm/decodal_wasm.js
+++ b/packages/decodal-wasm/decodal_wasm.js
@@ -40,25 +40,6 @@ export function evaluateProject(entry, files_json) {
         wasm.__wbindgen_free(deferred3_0, deferred3_1, 1);
     }
 }
-
-/**
- * @param {string} source
- * @returns {string}
- */
-export function formatSource(source) {
-    let deferred2_0;
-    let deferred2_1;
-    try {
-        const ptr0 = passStringToWasm0(source, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
-        const len0 = WASM_VECTOR_LEN;
-        const ret = wasm.formatSource(ptr0, len0);
-        deferred2_0 = ret[0];
-        deferred2_1 = ret[1];
-        return getStringFromWasm0(ret[0], ret[1]);
-    } finally {
-        wasm.__wbindgen_free(deferred2_0, deferred2_1, 1);
-    }
-}
 function __wbg_get_imports() {
     const import0 = {
         __proto__: null,
diff --git a/packages/decodal-wasm/decodal_wasm_bg.wasm b/packages/decodal-wasm/decodal_wasm_bg.wasm
index 5a6df24..c03a15e 100644
Binary files a/packages/decodal-wasm/decodal_wasm_bg.wasm and b/packages/decodal-wasm/decodal_wasm_bg.wasm differ
diff --git a/packages/decodal-wasm/decodal_wasm_bg.wasm.d.ts b/packages/decodal-wasm/decodal_wasm_bg.wasm.d.ts
index 3c35b37..4f894cc 100644
--- a/packages/decodal-wasm/decodal_wasm_bg.wasm.d.ts
+++ b/packages/decodal-wasm/decodal_wasm_bg.wasm.d.ts
@@ -3,7 +3,6 @@
 export const memory: WebAssembly.Memory;
 export const evaluate: (a: number, b: number) => [number, number];
 export const evaluateProject: (a: number, b: number, c: number, d: number) => [number, number];
-export const formatSource: (a: number, b: number) => [number, number];
 export const __wbindgen_externrefs: WebAssembly.Table;
 export const __wbindgen_malloc: (a: number, b: number) => number;
 export const __wbindgen_realloc: (a: number, b: number, c: number, d: number) => number;
diff --git a/site/decodal-site/scripts/prepare-wasm-package.mjs b/site/decodal-site/scripts/prepare-wasm-package.mjs
index d7ffe10..250aae1 100644
--- a/site/decodal-site/scripts/prepare-wasm-package.mjs
+++ b/site/decodal-site/scripts/prepare-wasm-package.mjs
@@ -34,15 +34,15 @@ deno add jsr:@hare/decodal-wasm
 ## Usage
 
 \`\`\`js
-import init, { evaluateProject, formatSource } from 'decodal-wasm';
+import init, { evaluateProject } from 'decodal-wasm';
 
 await init();
 
-const formatted = JSON.parse(formatSource('Server={port=Int default 8080;};'));
-console.log(formatted.source);
-
-const result = evaluateProject('main.dcdl', JSON.stringify({
-  'main.dcdl': 'Server = { port = Int default 8080; };',
+const result = evaluateProject(JSON.stringify({
+  entry: 'main.dcdl',
+  files: {
+    'main.dcdl': 'Server = { port = Int default 8080; };',
+  },
 }));
 
 console.log(JSON.parse(result));
diff --git a/site/decodal-site/src/lib/docs.js b/site/decodal-site/src/lib/docs.js
index 6be6cd1..ba791d9 100644
--- a/site/decodal-site/src/lib/docs.js
+++ b/site/decodal-site/src/lib/docs.js
@@ -20,7 +20,6 @@ export const docs = Object.fromEntries(
 export const nav = [
   { title: 'Introduction', slug: 'introduction' },
   { title: 'Components', slug: 'components' },
-  { title: 'Formatting', slug: 'formatting' },
   {
     title: 'Language Specification',
     slug: 'language',
diff --git a/site/decodal-site/src/pages/playground.astro b/site/decodal-site/src/pages/playground.astro
index 1a179a5..09af8ab 100644
--- a/site/decodal-site/src/pages/playground.astro
+++ b/site/decodal-site/src/pages/playground.astro
@@ -15,7 +15,6 @@ import ManualLayout from '../layouts/ManualLayout.astro';
         </label>
         <button id="load-example" type="button">Load</button>
         <p id="status" class="status">Loading WASM...</p>
-        <button id="format" disabled>Format</button>
         <button id="run" disabled>Run</button>
       </div>
     </div>
diff --git a/site/decodal-site/src/scripts/playground.js b/site/decodal-site/src/scripts/playground.js
index a613b6b..40c3447 100644
--- a/site/decodal-site/src/scripts/playground.js
+++ b/site/decodal-site/src/scripts/playground.js
@@ -1,4 +1,4 @@
-import init, { evaluateProject, formatSource } from 'decodal-wasm';
+import init, { evaluateProject } from 'decodal-wasm';
 import { EditorView, basicSetup } from 'codemirror';
 import { keymap } from '@codemirror/view';
 import { decodal } from 'decodal-codemirror';
@@ -10,7 +10,6 @@ const starterProject = playgroundExamples[0];
 const editorHost = document.getElementById('editor');
 const output = document.getElementById('output');
 const run = document.getElementById('run');
-const formatButton = document.getElementById('format');
 const status = document.getElementById('status');
 const fileTree = document.getElementById('file-tree');
 const activeFile = document.getElementById('active-file');
@@ -177,20 +176,6 @@ function execute() {
   output.classList.toggle('error', !result.ok);
 }
 
-function formatActiveFile() {
-  const result = JSON.parse(formatSource(getEditorText()));
-  if (!result.ok) {
-    output.textContent = result.error;
-    output.classList.add('error');
-    return;
-  }
-  setEditorText(result.source);
-  project.files[project.activePath] = result.source;
-  saveProject();
-  output.textContent = 'Formatted.';
-  output.classList.remove('error');
-}
-
 function renderFileTree() {
   const tree = buildTree(Object.keys(project.files).sort());
   fileTree.replaceChildren(renderTreeList(tree.children));
@@ -244,7 +229,6 @@ function compareNodes(a, b) {
 try {
   await init();
   run.disabled = false;
-  formatButton.disabled = false;
   status.textContent = '';
   execute();
 } catch (error) {
@@ -252,7 +236,6 @@ try {
 }
 
 run.addEventListener('click', execute);
-formatButton.addEventListener('click', formatActiveFile);
 loadExample.addEventListener('click', () => {
   const example = playgroundExamples.find((item) => item.id === exampleSelect.value);
   if (!example) return;