diff --git a/bank_core/src/transaction.rs b/bank_core/src/transaction.rs
index e83f9ad..89920a2 100644
--- a/bank_core/src/transaction.rs
+++ b/bank_core/src/transaction.rs
@@ -22,8 +22,8 @@ pub struct Transaction {
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq)]
 #[cfg_attr(feature = "schemas", derive(schemars::JsonSchema))]
 pub struct FullTransaction {
-    pub from: Participant,
-    pub to: Participant,
+    pub from: Option<Participant>,
+    pub to: Option<Participant>,
     pub amount: u64,
     pub timestamp: DateTime<Utc>,
     pub message: Option<String>,
@@ -39,9 +39,14 @@ pub enum Direction {
 
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq)]
 #[cfg_attr(feature = "schemas", derive(schemars::JsonSchema))]
-pub struct Participant {
-    pub user: User,
-    pub account: ReducedAccountInfo,
+#[serde(untagged)]
+pub enum Participant {
+    Normal {
+        user: User,
+        account: ReducedAccountInfo,
+    },
+    /// interop username
+    Interop(String),
 }
 
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq)]
diff --git a/migrations/000000_baseline.sql b/migrations/000000_baseline.sql
index c2519b1..14dca0b 100644
--- a/migrations/000000_baseline.sql
+++ b/migrations/000000_baseline.sql
@@ -14,11 +14,17 @@ create table accounts(
 
 create table transactions(
     id uuid primary key,
-    "from" uuid not null references accounts(id),
-    "to" uuid not null references accounts(id),
+    "from" uuid references accounts(id),
+    "to" uuid references accounts(id),
+    interop_name text,
+    system bool not null default false,
     amount bigint not null constraint positive_amount check (amount > 0),
     timestamp timestamp with time zone not null default now(),
-    message text
+    message text,
+    constraint check_interop_name_from_to_null check (
+        ((("from" is null and "to" is not null) or ("from" is not null and "to" is null)) and (interop_name is not null or system)) or
+        ("from" is not null and "to" is not null and interop_name is null)
+    )
 );
 
 create index transactions_from on transactions ("from");
@@ -28,6 +34,12 @@ create view transactions_with_user_info as select
     t.amount,
     t.message,
     t.timestamp,
+    t.system,
+    case
+        when t."from" is null then t.interop_name
+        when t."to" is null then t.interop_name
+        else null
+    end as interop_name,
     -- From Participant
     uf.id AS from_user_id,
     t."from" as from_account_id,
diff --git a/src/config.rs b/src/config.rs
index 8fc7e90..14e7648 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -11,12 +11,24 @@ pub struct Config {
     #[serde(default = "default_port")]
     pub port: u16,
     pub jwt_key: String,
+    #[serde(default = "default_interop_key")]
+    pub interop_key: String,
+    #[serde(default = "default_interop_prefix")]
+    pub interop_prefix: String,
 }
 
 fn default_host() -> IpAddr {
     IpAddr::V6(Ipv6Addr::LOCALHOST)
 }
 
+fn default_interop_key() -> String {
+    "".into()
+}
+
+fn default_interop_prefix() -> String {
+    "".into()
+}
+
 fn default_port() -> u16 {
     3845
 }
diff --git a/src/model/transaction.rs b/src/model/transaction.rs
index fcd5869..ed56469 100644
--- a/src/model/transaction.rs
+++ b/src/model/transaction.rs
@@ -11,33 +11,59 @@ use uuid::{NoContext, Timestamp, Uuid};
 use crate::model::count;
 
 fn full_transaction_from_row(row: Row) -> FullTransaction {
+    let system: bool = row.get("system");
     FullTransaction {
-        from: Participant {
-            user: User {
-                id: row.get("from_user_id"),
-                name: row.get("from_user_name"),
-            },
-            account: ReducedAccountInfo {
-                id: row.get("from_account_id"),
-                name: row.get("from_account_name"),
-            },
-        },
-        to: Participant {
-            user: User {
-                id: row.get("to_user_id"),
-                name: row.get("to_user_name"),
-            },
-            account: ReducedAccountInfo {
-                id: row.get("to_account_id"),
-                name: row.get("to_account_name"),
-            },
-        },
+        from: participant_from_row(
+            &row,
+            system,
+            "from_user_id",
+            "from_user_name",
+            "from_account_id",
+            "to_account_name",
+        ),
+        to: participant_from_row(
+            &row,
+            system,
+            "to_user_id",
+            "to_user_name",
+            "to_account_id",
+            "to_account_name",
+        ),
         timestamp: row.get("timestamp"),
         amount: row.get::<_, i64>("amount") as u64,
         message: row.get("message"),
     }
 }
 
+fn participant_from_row(
+    row: &Row,
+    system: bool,
+    user_id: &str,
+    user_name: &str,
+    account_id: &str,
+    account_name: &str,
+) -> Option<Participant> {
+    if let Some(user_id) = row.get::<_, Option<Uuid>>(user_id) {
+        let user_name = row.get(user_name);
+        let account_id = row.get(account_id);
+        let account_name = row.get(account_name);
+        Some(Participant::Normal {
+            user: User {
+                id: user_id,
+                name: user_name,
+            },
+            account: ReducedAccountInfo {
+                id: account_id,
+                name: account_name,
+            },
+        })
+    } else if system {
+        None
+    } else {
+        Some(Participant::Interop(row.get("interop_name")))
+    }
+}
+
 pub struct Transactions;
 
 impl Transactions {