diff --git a/src/main.rs b/src/main.rs
index 0c6dd57..462026e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -115,7 +115,7 @@ fn main() -> Result<(), Box<dyn Error>> {
             plan,
             plan_id,
         } => {
-            let plan = Lookup::try_from((plan, plan_id))?;
+            let plan = Lookup::from_options(plan, plan_id)?;
             let accounts = Ynab::new(&token).list_accounts(plan)?;
             println!("Available accounts in plan:");
             for account in accounts {
@@ -132,8 +132,8 @@ fn main() -> Result<(), Box<dyn Error>> {
             format,
             inputs,
         } => {
-            let plan = Lookup::try_from((plan, plan_id))?;
-            let account = Lookup::try_from((account, account_id))?;
+            let plan = Lookup::from_options(plan, plan_id)?;
+            let account = Lookup::from_options(account, account_id)?;
 
             let transactions = read_transactions_from(&inputs, &format)?;
 
diff --git a/src/ynab.rs b/src/ynab/client.rs
similarity index 61%
rename from src/ynab.rs
rename to src/ynab/client.rs
index b4fe59b..556fbf9 100644
--- a/src/ynab.rs
+++ b/src/ynab/client.rs
@@ -1,65 +1,7 @@
+use super::lookup::Lookup;
+use super::transform;
+use super::types;
 use crate::Transaction;
-use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
-
-#[derive(Debug, Serialize)]
-struct YnabTransaction {
-    import_id: String,
-    date: String,
-    amount: i64,
-    payee_name: String,
-    account_id: String,
-}
-
-#[derive(Serialize, Deserialize, Debug)]
-struct YnabResponse<T> {
-    data: T,
-}
-
-#[derive(Deserialize, Debug)]
-struct YnabPlanList {
-    plans: Vec<YnabPlan>,
-}
-
-#[derive(Deserialize, Debug)]
-struct YnabPlan {
-    id: String,
-    name: String,
-}
-
-#[derive(Deserialize, Debug)]
-struct YnabAccountList {
-    accounts: Vec<YnabAccount>,
-}
-
-#[derive(Deserialize, Debug)]
-struct YnabAccount {
-    id: String,
-    name: String,
-}
-
-#[derive(Serialize, Debug)]
-struct YnabTransactionList {
-    transactions: Vec<YnabTransaction>,
-}
-
-#[derive(Debug)]
-pub enum Lookup {
-    Name(String),
-    Id(String),
-}
-
-impl TryFrom<(Option<String>, Option<String>)> for Lookup {
-    type Error = String;
-
-    fn try_from((name, id): (Option<String>, Option<String>)) -> Result<Self, Self::Error> {
-        match (name, id) {
-            (Some(name), _) => Ok(Lookup::Name(name)),
-            (_, Some(id)) => Ok(Lookup::Id(id)),
-            _ => Err("must provide name or id".to_owned()),
-        }
-    }
-}
 
 pub struct Ynab {
     token: String,
@@ -79,7 +21,7 @@ impl Ynab {
             Lookup::Id(id) => Ok(id),
             Lookup::Name(name) => {
                 let url = "plans";
-                let res: YnabResponse<YnabPlanList> = serde_json::from_str(
+                let res: types::YnabResponse<types::YnabPlanList> = serde_json::from_str(
                     &self.get(url).map_err(|e| format!("request error: {}", e))?,
                 )
                 .map_err(|e| format!("parse error: {}", e))?;
@@ -98,7 +40,7 @@ impl Ynab {
             Lookup::Id(id) => Ok(id),
             Lookup::Name(name) => {
                 let url = format!("plans/{}/accounts", plan_id);
-                let res: YnabResponse<YnabAccountList> = serde_json::from_str(
+                let res: types::YnabResponse<types::YnabAccountList> = serde_json::from_str(
                     &self
                         .get(&url)
                         .map_err(|e| format!("request error: {}", e))?,
@@ -114,7 +56,7 @@ impl Ynab {
         }
     }
 
-    fn get(&self, request: &str) -> Result<String, reqwest::Error> {
+    pub(crate) fn get(&self, request: &str) -> Result<String, reqwest::Error> {
         const URL: &str = "https://api.ynab.com/v1/";
         let request = format!("{}{}", URL, request);
         let res = self
@@ -151,7 +93,7 @@ impl Ynab {
 
     pub fn list_plans(&self) -> Result<Vec<String>, String> {
         let url = String::from("plans");
-        let res: YnabResponse<YnabPlanList> = serde_json::from_str(
+        let res: types::YnabResponse<types::YnabPlanList> = serde_json::from_str(
             &self
                 .get(&url)
                 .map_err(|e| format!("request error: {}", e))?,
@@ -163,7 +105,7 @@ impl Ynab {
     pub fn list_accounts(&self, plan: Lookup) -> Result<Vec<String>, String> {
         let plan_id = self.resolve_plan(plan)?;
         let url = format!("plans/{}/accounts", plan_id);
-        let res: YnabResponse<YnabAccountList> = serde_json::from_str(
+        let res: types::YnabResponse<types::YnabAccountList> = serde_json::from_str(
             &self
                 .get(&url)
                 .map_err(|e| format!("request error: {}", e))?,
@@ -172,32 +114,6 @@ impl Ynab {
         Ok(res.data.accounts.into_iter().map(|p| p.name).collect())
     }
 
-    fn ynab_transactions(
-        &self,
-        transactions: &[Transaction],
-        account_id: &str,
-    ) -> Vec<YnabTransaction> {
-        let mut result = Vec::new();
-        let mut idmap: HashMap<(String, i64), u32> = HashMap::new();
-        for t in transactions {
-            let key = (t.date.clone(), t.amount);
-            let id = {
-                let n = idmap.entry(key).or_insert(0);
-                *n += 1;
-                *n
-            };
-            let y = YnabTransaction {
-                import_id: format!("YNAB:{}:{}:{}", t.amount, t.date, id),
-                date: t.date.clone(),
-                amount: t.amount,
-                payee_name: t.payee.clone(),
-                account_id: account_id.to_string(),
-            };
-            result.push(y);
-        }
-        result
-    }
-
     pub fn upload(
         &self,
         transactions: &[Transaction],
@@ -207,8 +123,8 @@ impl Ynab {
         let plan_id = self.resolve_plan(plan)?;
         let account_id = self.resolve_account(&plan_id, account)?;
         let request = format!("plans/{}/transactions", plan_id);
-        let body = serde_json::to_string(&YnabTransactionList {
-            transactions: self.ynab_transactions(transactions, &account_id),
+        let body = serde_json::to_string(&types::YnabTransactionList {
+            transactions: transform::ynab_transactions(transactions, &account_id),
         })
         .map_err(|e| format!("transaction format error: {}", e))?;
         println!("{}", body);
diff --git a/src/ynab/lookup.rs b/src/ynab/lookup.rs
new file mode 100644
index 0000000..66e4597
--- /dev/null
+++ b/src/ynab/lookup.rs
@@ -0,0 +1,14 @@
+pub enum Lookup {
+    Name(String),
+    Id(String),
+}
+
+impl Lookup {
+    pub fn from_options(name: Option<String>, id: Option<String>) -> Result<Self, String> {
+        match (name, id) {
+            (Some(name), _) => Ok(Self::Name(name)),
+            (_, Some(id)) => Ok(Self::Id(id)),
+            _ => Err("must provide name or id".to_owned()),
+        }
+    }
+}
diff --git a/src/ynab/mod.rs b/src/ynab/mod.rs
new file mode 100644
index 0000000..1a97bbc
--- /dev/null
+++ b/src/ynab/mod.rs
@@ -0,0 +1,9 @@
+mod lookup;
+pub use lookup::Lookup;
+
+mod types;
+
+mod client;
+pub use client::Ynab;
+
+mod transform;
diff --git a/src/ynab/transform.rs b/src/ynab/transform.rs
new file mode 100644
index 0000000..ae03b5f
--- /dev/null
+++ b/src/ynab/transform.rs
@@ -0,0 +1,28 @@
+use super::types;
+use crate::Transaction;
+use std::collections::HashMap;
+
+pub(crate) fn ynab_transactions(
+    transactions: &[Transaction],
+    account_id: &str,
+) -> Vec<types::YnabTransaction> {
+    let mut result = Vec::new();
+    let mut idmap: HashMap<(String, i64), u32> = HashMap::new();
+    for t in transactions {
+        let key = (t.date.clone(), t.amount);
+        let id = {
+            let n = idmap.entry(key).or_insert(0);
+            *n += 1;
+            *n
+        };
+        let y = types::YnabTransaction {
+            import_id: format!("YNAB:{}:{}:{}", t.amount, t.date, id),
+            date: t.date.clone(),
+            amount: t.amount,
+            payee_name: t.payee.clone(),
+            account_id: account_id.to_string(),
+        };
+        result.push(y);
+    }
+    result
+}
diff --git a/src/ynab/types.rs b/src/ynab/types.rs
new file mode 100644
index 0000000..36c92f5
--- /dev/null
+++ b/src/ynab/types.rs
@@ -0,0 +1,42 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Serialize)]
+pub(crate) struct YnabTransaction {
+    pub(crate) import_id: String,
+    pub(crate) date: String,
+    pub(crate) amount: i64,
+    pub(crate) payee_name: String,
+    pub(crate) account_id: String,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub(crate) struct YnabResponse<T> {
+    pub(crate) data: T,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct YnabPlanList {
+    pub(crate) plans: Vec<YnabPlan>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct YnabPlan {
+    pub(crate) id: String,
+    pub(crate) name: String,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct YnabAccountList {
+    pub(crate) accounts: Vec<YnabAccount>,
+}
+
+#[derive(Deserialize, Debug)]
+pub(crate) struct YnabAccount {
+    pub(crate) id: String,
+    pub(crate) name: String,
+}
+
+#[derive(Serialize, Debug)]
+pub(crate) struct YnabTransactionList {
+    pub(crate) transactions: Vec<YnabTransaction>,
+}