diff --git a/CHANGELOG.md b/CHANGELOG.md
index 80c6fd79f1..e684f7dea9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `jj config list` command prints values from config (with other subcommands
   coming soon).
 
+* `jj debug config-schema` command prints out JSON (and TOML) schema
+  for jj config files.
+
 ### Fixed bugs
 
 * When sharing the working copy with a Git repo, we used to forget to export
diff --git a/Cargo.lock b/Cargo.lock
index e73ede0199..fa8b8a026e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -708,6 +708,7 @@ dependencies = [
  "console",
  "lazy_static",
  "linked-hash-map",
+ "regex",
  "similar",
  "yaml-rust",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 0be3957628..8a4db6b9b1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -68,7 +68,7 @@ libc = { version = "0.2.139" }
 assert_cmd = "2.0.7"
 criterion = "0.4.0"
 criterion_bencher_compat = "0.4.0"
-insta = "1.23.0"
+insta = { version = "1.23.0", features = ["filters"] }
 predicates = "2.1.5"
 regex = "1.7.0"
 test-case = "2.2.2"
diff --git a/src/commands.rs b/src/commands.rs
index 0df07ec8a1..6a2101d6e2 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -999,6 +999,7 @@ struct GitExportArgs {}
 enum DebugCommands {
     Completion(DebugCompletionArgs),
     Mangen(DebugMangenArgs),
+    ConfigSchema(DebugConfigSchemaArgs),
     #[command(name = "resolverev")]
     ResolveRev(DebugResolveRevArgs),
     #[command(name = "workingcopy")]
@@ -1043,6 +1044,10 @@ struct DebugCompletionArgs {
 #[derive(clap::Args, Clone, Debug)]
 struct DebugMangenArgs {}
 
+/// Print the JSON schema for jj's TOML config format.
+#[derive(clap::Args, Clone, Debug)]
+struct DebugConfigSchemaArgs {}
+
 /// Resolve a revision identifier to its full ID
 #[derive(clap::Args, Clone, Debug)]
 struct DebugResolveRevArgs {
@@ -3174,6 +3179,11 @@ fn cmd_debug(
             man.render(&mut buf)?;
             ui.stdout_formatter().write_all(&buf)?;
         }
+        DebugCommands::ConfigSchema(_config_schema_matches) => {
+            // TODO(#879): Consider generating entire schema dynamically vs. using static file.
+            let buf = include_bytes!("config-schema.json");
+            ui.stdout_formatter().write_all(buf)?;
+        }
         DebugCommands::ResolveRev(resolve_matches) => {
             let workspace_command = command.workspace_helper(ui)?;
             let commit = workspace_command.resolve_single_rev(&resolve_matches.revision)?;
diff --git a/tests/test_debug_command.rs b/tests/test_debug_command.rs
new file mode 100644
index 0000000000..2a0aede6dc
--- /dev/null
+++ b/tests/test_debug_command.rs
@@ -0,0 +1,56 @@
+// Copyright 2022 The Jujutsu Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use insta::assert_snapshot;
+use regex::Regex;
+
+use crate::common::TestEnvironment;
+
+pub mod common;
+
+#[test]
+fn test_debug_config_schema() {
+    let test_env = TestEnvironment::default();
+    let stdout = test_env.jj_cmd_success(test_env.env_root(), &["debug", "config-schema"]);
+    let expected_schema_re = Regex::new(r"(?s)^\{\n.*\n\}\n").unwrap();
+    assert!(
+        expected_schema_re.is_match(&stdout),
+        "output didn't match format {expected_schema_re:?}:\n{stdout}"
+    );
+}
+
+#[test]
+fn test_debug_index() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "repo", "--git"]);
+    let workspace_path = test_env.env_root().join("repo");
+    let stdout = test_env.jj_cmd_success(&workspace_path, &["debug", "index"]);
+    insta::with_settings!(
+    {filters => vec![
+        (r"    Name: [0-9a-z]+", "    Name: [hash]"),
+    ]},
+    {
+        assert_snapshot!(stdout, @r###"
+            Number of commits: 2
+            Number of merges: 0
+            Max generation number: 1
+            Number of heads: 1
+            Number of changes: 2
+            Stats per level:
+            Level 0:
+                Number of commits: 2
+                Name: [hash]
+            "###)
+    });
+}