diff --git a/api/src/controllers/api/mod.rs b/api/src/controllers/api/mod.rs
index 8072460..9c9c221 100644
--- a/api/src/controllers/api/mod.rs
+++ b/api/src/controllers/api/mod.rs
@@ -10,6 +10,7 @@ pub mod pept2taxa;
 pub mod peptinfo;
 pub mod protinfo;
 pub mod taxa2lca;
+pub mod taxa2rank;
 pub mod taxa2tree;
 pub mod taxonomy;
 
diff --git a/api/src/controllers/api/taxa2rank.rs b/api/src/controllers/api/taxa2rank.rs
new file mode 100644
index 0000000..07c5368
--- /dev/null
+++ b/api/src/controllers/api/taxa2rank.rs
@@ -0,0 +1,80 @@
+use std::collections::HashMap;
+
+use axum::{extract::State, Json};
+use itertools::Itertools;
+use serde::{Deserialize, Serialize};
+
+use datastore::LineageStore;
+use crate::{
+    controllers::generate_handlers,
+    helpers::lineage_helper::{get_lineage_array, LineageVersion},
+    AppState
+};
+use crate::errors::ApiError;
+
+#[derive(Deserialize)]
+pub struct Parameters {
+    /// Vector of taxa vectors, one per peptide
+    taxa: Vec<Vec<u32>>,
+    /// The rank to map taxa to (e.g., "species", "genus", "family")
+    rank: String,
+}
+
+#[derive(Serialize)]
+pub struct RankMappingResult {
+    /// The mapped taxa at the specified rank
+    mapped_taxa: Vec<Vec<u32>>,
+}
+
+/// Maps taxa to a specific taxonomic rank with caching for duplicate taxa.
+/// Uses a HashMap to cache lineage lookups, which is more efficient when there are many duplicates.
+async fn handler(
+    State(AppState { datastore, .. }): State<AppState>,
+    Parameters { taxa, rank }: Parameters,
+) -> Result<RankMappingResult, ApiError> {
+
+    let rank_lowercase = rank.to_lowercase();
+    let rank_idx = LineageStore::rank_to_idx(&rank_lowercase)
+        .ok_or_else(|| ApiError::UnknownRankError(format!("Invalid rank: {}", rank)))?;
+
+    let lineage_store = datastore.lineage_store();
+
+    // Build a cache of taxon_id -> taxon_id_at_rank mappings
+    let mut cache: HashMap<u32, Option<u32>> = HashMap::new();
+
+    let mapped_taxa: Vec<Vec<u32>> = taxa
+        .iter()
+        .map(|taxa_vec| {
+            taxa_vec
+                .iter()
+                .filter_map(|taxon_id| {
+                    let mapped_taxon = cache.entry(*taxon_id).or_insert_with(|| {
+                        let lineage = get_lineage_array(*taxon_id, LineageVersion::V2, lineage_store);
+                        lineage
+                            .get(rank_idx)
+                            .and_then(|taxon| *taxon)
+                            .map(|taxon_id| taxon_id as u32)
+                    });
+
+                    *mapped_taxon
+                })
+                .unique()
+                .collect()
+        })
+        .collect();
+
+    Ok(RankMappingResult {
+        mapped_taxa,
+    })
+}
+
+// Default handler without cache
+generate_handlers!(
+    async fn json_handler(
+        state => State<AppState>,
+        params => Parameters
+    ) -> Result<Json<RankMappingResult>, ApiError> {
+        Ok(Json(handler(state, params).await?))
+    }
+);
+
diff --git a/api/src/routes.rs b/api/src/routes.rs
index 4efae4e..b933ff2 100644
--- a/api/src/routes.rs
+++ b/api/src/routes.rs
@@ -15,7 +15,7 @@ use crate::{
     controllers::{
         api::{
             pept2ec, pept2funct, pept2go, pept2interpro, pept2lca, pept2prot, pept2taxa, peptinfo, protinfo, taxa2lca,
-            taxa2tree, taxonomy
+               taxa2rank, taxa2tree, taxonomy
         },
         datasets::sampledata,
         mpa::{pept2data},
@@ -103,7 +103,9 @@ fn create_api_v2_routes() -> Router<AppState> {
         "/taxa2tree",
         get(taxa2tree::get_json_handler_v2).post(taxa2tree::post_json_handler_v2),
         "/taxonomy",
-        get(taxonomy::get_json_handler_v2).post(taxonomy::post_json_handler_v2)
+        get(taxonomy::get_json_handler_v2).post(taxonomy::post_json_handler_v2),
+       "/taxa2rank",
+       get(taxa2rank::get_json_handler).post(taxa2rank::post_json_handler)
     )
     .route("/taxa2tree.html", get(taxa2tree::get_html_handler_v2).post(taxa2tree::post_html_handler_v2))
 }