diff --git a/Cargo.lock b/Cargo.lock
index 3560d70ddd..cbb8f41f43 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1532,6 +1532,17 @@ dependencies = [
  "stdweb 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "iotool"
+version = "0.1.0"
+dependencies = [
+ "abstutil 0.1.0",
+ "geom 0.1.0",
+ "map_model 0.1.0",
+ "serde 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sim 0.1.0",
+]
+
 [[package]]
 name = "iovec"
 version = "0.1.4"
@@ -3342,17 +3353,6 @@ dependencies = [
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "traffic_importer"
-version = "0.1.0"
-dependencies = [
- "abstutil 0.1.0",
- "geom 0.1.0",
- "map_model 0.1.0",
- "serde 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
- "sim 0.1.0",
-]
-
 [[package]]
 name = "try-lock"
 version = "0.2.2"
diff --git a/Cargo.toml b/Cargo.toml
index ab62ac4b9b..f67cb07c2a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,11 +8,11 @@ members = [
   "geom",
   "headless",
   "importer",
+  "iotool",
   "kml",
   "map_editor",
   "map_model",
   "sim",
-  "traffic_importer",
   "updater",
 ]
 
diff --git a/book/src/api.md b/book/src/api.md
index 42bb2c65ee..6b05ae0417 100644
--- a/book/src/api.md
+++ b/book/src/api.md
@@ -37,3 +37,19 @@ are missing, etc. A summary of the commands available so far:
     mode, duration of trip in seconds). The mode is either a string like "Walk"
     or "Drive", or null if the trip was aborted (due to a simulation bug or
     disconnected map).
+
+## Related tools
+
+There's no API to create trips. Instead, you can
+[import trips from your own data](https://dabreegster.github.io/abstreet/trafficsim/travel_demand.html#custom-import).
+
+If you need to deeply inspect the map, you can dump it to JSON:
+
+```
+cargo run --bin iotool -- dump_map --map=data/system/maps/montlake.bin
+```
+
+The format of the map isn't well-documented yet. See the
+[generated API docs](https://dabreegster.github.io/abstreet/rustdoc/map_model/index.html)
+and [the map model docs](https://dabreegster.github.io/abstreet/map/index.html)
+in the meantime.
diff --git a/book/src/howto/dev.md b/book/src/howto/dev.md
index 7e8c706267..8d6a016943 100644
--- a/book/src/howto/dev.md
+++ b/book/src/howto/dev.md
@@ -23,6 +23,7 @@ One-time setup:
 
 ## Development tips
 
+- [Generated API documentation](https://dabreegster.github.io/abstreet/rustdoc/map_model/index.html)
 - Compile faster by just doing `cargo run`. The executable will have debug stack
   traces and run more slowly. You can do `cargo run --release` to build in
   optimized release mode; compilation will be slower, but the executable much
@@ -136,6 +137,7 @@ Common utilities:
 - `abstutil`: a grab-bag of IO helpers, timing and logging utilities, etc
 - `geom`: types for GPS and map-space points, lines, angles, polylines,
   polygons, circles, durations, speeds
+- `iotool`: a catch-all tool to import/export data
 
 ## Code conventions
 
diff --git a/book/src/trafficsim/travel_demand.md b/book/src/trafficsim/travel_demand.md
index 398710074d..d030047e57 100644
--- a/book/src/trafficsim/travel_demand.md
+++ b/book/src/trafficsim/travel_demand.md
@@ -92,7 +92,7 @@ example:
 Run the tool:
 
 ```
-cargo run --bin traffic_importer -- --map=data/system/maps/montlake.bin --input=/path/to/input.json
+cargo run --bin iotool -- import_traffic --map=data/system/maps/montlake.bin --input=/path/to/input.json
 ```
 
 The tool matches input positions to the nearest building or border intersection,
diff --git a/traffic_importer/Cargo.toml b/iotool/Cargo.toml
similarity index 90%
rename from traffic_importer/Cargo.toml
rename to iotool/Cargo.toml
index 9876eec942..ed49657793 100644
--- a/traffic_importer/Cargo.toml
+++ b/iotool/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "traffic_importer"
+name = "iotool"
 version = "0.1.0"
 authors = ["Dustin Carlino <dabreegster@gmail.com>"]
 edition = "2018"
diff --git a/traffic_importer/src/main.rs b/iotool/src/main.rs
similarity index 81%
rename from traffic_importer/src/main.rs
rename to iotool/src/main.rs
index 4eb0663f0f..767199c6a8 100644
--- a/traffic_importer/src/main.rs
+++ b/iotool/src/main.rs
@@ -6,10 +6,21 @@ use sim::{IndividTrip, PersonID, PersonSpec, Scenario, SpawnTrip, TripEndpoint,
 
 fn main() {
     let mut args = CmdArgs::new();
-    let map = args.required("--map");
-    let input = args.required("--input");
-    args.done();
+    match args.required_free().as_ref() {
+        "import_traffic" => {
+            import_traffic(args.required("--map"), args.required("--input"));
+            args.done();
+        }
+        "dump_map" => {
+            let map = Map::new(args.required("--map"), &mut Timer::new("dump map"));
+            println!("{}", abstutil::to_json(&map));
+            args.done();
+        }
+        x => panic!("Unknown command {}. Try: import_traffic, dump_map", x),
+    }
+}
 
+fn import_traffic(map: String, input: String) {
     let mut timer = Timer::new("import traffic demand data");
     let map = Map::new(map, &mut timer);
     let input: Input = abstutil::read_json(input, &mut timer);