diff --git a/tidepool/src/main.rs b/tidepool/src/main.rs
index 8821eda..eff3ecf 100644
--- a/tidepool/src/main.rs
+++ b/tidepool/src/main.rs
@@ -61,7 +61,7 @@ fn create_mailbox() -> (mpsc::SyncSender<Msg>, mpsc::Receiver<Msg>) {
 }
 
 fn single(args: SingleRun) -> Result<()> {
-    let config = parse_config_file(&args.config_file)?;
+    let config = read_config_file(&args.config_file)?;
 
     let (tx, rx) = create_mailbox();
     let exit_early = Arc::new(atomic::AtomicBool::new(false));
@@ -114,7 +114,7 @@ fn single(args: SingleRun) -> Result<()> {
 }
 
 fn multi(args: MultiRun) -> Result<()> {
-    let config = parse_config_file(&args.config_file)?;
+    let config = read_config_file(&args.config_file)?;
 
     let (tx, rx) = create_mailbox();
     let tasks = args.count.map_or(i64::MAX, |n| n as i64);
@@ -182,13 +182,33 @@ fn multi(args: MultiRun) -> Result<()> {
     Ok(())
 }
 
-fn parse_config_file(path: &Path) -> Result<Config> {
+fn read_config_file(path: &Path) -> Result<Config> {
+    enum Format {
+        Json,
+        Toml,
+    }
+
+    let extension = path.extension().and_then(|e| e.to_str());
+    let format = match extension {
+        Some(e) if e.eq_ignore_ascii_case("json") => Format::Json,
+        Some(e) if e.eq_ignore_ascii_case("toml") => Format::Toml,
+        _ => {
+            return Err(anyhow::anyhow!(
+                "invalid config file extension, supports .toml or .json"
+            ));
+        }
+    };
+
     let mut contents = String::new();
     std::fs::File::open(path)
         .with_context(|| format!("error opening config file '{}'", path.display()))?
         .read_to_string(&mut contents)
         .context("error reading config file")?;
-    toml::from_str(&contents).context("error parsing config file")
+
+    match format {
+        Format::Json => serde_json::from_str(&contents).context("error parsing config file"),
+        Format::Toml => toml::from_str(&contents).context("error parsing config file"),
+    }
 }
 
 fn write_output(io_args: &IoArgs, path: Option<&Path>, output: &Output) -> Result<()> {