diff --git a/.yamlfmt b/.yamlfmt
new file mode 100644
index 0000000..7f2250d
--- /dev/null
+++ b/.yamlfmt
@@ -0,0 +1,4 @@
+formatter:
+  type: basic
+  indent: 2
+  retain_line_breaks: true
diff --git a/.yamlfmt.manifests b/.yamlfmt.manifests
new file mode 100644
index 0000000..0c3b230
--- /dev/null
+++ b/.yamlfmt.manifests
@@ -0,0 +1,4 @@
+formatter:
+  type: basic
+  indent: 4
+  retain_line_breaks: true
diff --git a/justfile b/justfile
index 740083a..c948742 100644
--- a/justfile
+++ b/justfile
@@ -6,6 +6,9 @@
 TEMPLATES_REPO := "git@github.com:ethereum-optimism/devnet-templates.git"
 TEMPLATES_BRANCH := "main"
 
+# Devnet folders whose YAML files are formatted (indent config lives in .yamlfmt)
+YAML_DIRS := "dev stg prod"
+
 # Default: show help
 default:
     @just --list
@@ -106,3 +109,28 @@ create-devnet net_type name preset:
     echo "Next steps:"
     echo "  1. Edit $TARGET_DIR/manifest.yaml to configure your devnet"
     echo "  2. Edit $TARGET_DIR/inventory.yaml to configure nodes and services"
+
+# Fix YAML indentation/formatting in place across dev/stg/prod devnet folders.
+# manifest.yaml uses 4-space, all other YAML uses 2-space, matching netchef output.
+fmt-yaml:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    dirs=()
+    for d in {{YAML_DIRS}}; do [ -d "$d" ] && dirs+=("$d"); done
+    [ ${#dirs[@]} -eq 0 ] && exit 0
+    manifests=(); while IFS= read -r f; do manifests+=("$f"); done < <(find "${dirs[@]}" -name manifest.yaml)
+    others=();    while IFS= read -r f; do others+=("$f"); done < <(find "${dirs[@]}" -name '*.yaml' ! -name manifest.yaml)
+    if [ ${#manifests[@]} -gt 0 ]; then mise exec -- yamlfmt -conf .yamlfmt.manifests "${manifests[@]}"; fi
+    if [ ${#others[@]} -gt 0 ]; then mise exec -- yamlfmt "${others[@]}"; fi
+
+# Check YAML formatting without writing changes (fails if any file needs formatting)
+lint-yaml:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    dirs=()
+    for d in {{YAML_DIRS}}; do [ -d "$d" ] && dirs+=("$d"); done
+    [ ${#dirs[@]} -eq 0 ] && exit 0
+    manifests=(); while IFS= read -r f; do manifests+=("$f"); done < <(find "${dirs[@]}" -name manifest.yaml)
+    others=();    while IFS= read -r f; do others+=("$f"); done < <(find "${dirs[@]}" -name '*.yaml' ! -name manifest.yaml)
+    if [ ${#manifests[@]} -gt 0 ]; then mise exec -- yamlfmt -lint -conf .yamlfmt.manifests "${manifests[@]}"; fi
+    if [ ${#others[@]} -gt 0 ]; then mise exec -- yamlfmt -lint "${others[@]}"; fi
diff --git a/mise.toml b/mise.toml
index 4cea2a5..a538dd7 100644
--- a/mise.toml
+++ b/mise.toml
@@ -1,4 +1,5 @@
 [tools]
 mdbook = "v0.4.43"
 uv = "0.9.5"
-"pipx:cookiecutter" = "2.6.0"
\ No newline at end of file
+"pipx:cookiecutter" = "2.6.0"
+yamlfmt = "0.21.0"