diff --git a/Cargo.toml b/Cargo.toml
index 04895de..3f05f63 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,3 +15,11 @@ bincode = "2.0.0-rc.3"
 fixedbitset = "0.5.7"
 nom = "7.1.3"
 petgraph = "0.6.5"
+
+[[bin]]
+name = "ringo-index"
+path = "src/ringo/ringo/index/main.rs"
+
+[[bin]]
+name = "ringo-search"
+path = "src/ringo/ringo/search/main.rs"
diff --git a/src/bin.rs b/src/bin.rs
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/src/bin.rs
@@ -0,0 +1 @@
+
diff --git a/src/lib.rs b/src/lib.rs
index d58a822..6424c7f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1 +1,2 @@
+mod bin;
 pub mod ringo;
diff --git a/src/ringo.rs b/src/ringo.rs
index 76b46a1..ee49d68 100644
--- a/src/ringo.rs
+++ b/src/ringo.rs
@@ -1,3 +1,4 @@
+pub mod fingerprint;
 pub mod math;
 pub mod molecule;
 mod ringo;
diff --git a/src/ringo/fingerprint.rs b/src/ringo/fingerprint.rs
new file mode 100644
index 0000000..c2d67fd
--- /dev/null
+++ b/src/ringo/fingerprint.rs
@@ -0,0 +1 @@
+pub mod fingerprint;
diff --git a/src/ringo/ringo/fingerprint.rs b/src/ringo/fingerprint/fingerprint.rs
similarity index 86%
rename from src/ringo/ringo/fingerprint.rs
rename to src/ringo/fingerprint/fingerprint.rs
index c0fd772..dc97a66 100644
--- a/src/ringo/ringo/fingerprint.rs
+++ b/src/ringo/fingerprint/fingerprint.rs
@@ -32,7 +32,7 @@ impl<'de> bincode::BorrowDecode<'de> for Fingerprint {
 
 #[cfg(test)]
 mod tests {
-    use crate::ringo::ringo::fingerprint::{Fingerprint, FINGERPRINT_SIZE};
+    use crate::ringo::fingerprint::fingerprint::{Fingerprint, FINGERPRINT_SIZE};
     use fixedbitset::FixedBitSet;
 
     #[test]
@@ -44,10 +44,9 @@ mod tests {
         let mut buf = vec![0u8; FINGERPRINT_SIZE / 8];
         bincode::encode_into_slice(&fp, buf.as_mut_slice(), bincode::config::standard()).unwrap();
 
-        let decoded: Fingerprint =
-            bincode::decode_from_slice(&buf, bincode::config::standard())
-                .unwrap()
-                .0;
+        let decoded: Fingerprint = bincode::decode_from_slice(&buf, bincode::config::standard())
+            .unwrap()
+            .0;
         assert_eq!(decoded.0.ones().collect::<Vec<usize>>(), vec![1, 17]);
     }
 }
diff --git a/src/ringo/molecule/model/atom.rs b/src/ringo/molecule/model/atom.rs
index 6fcde13..521be5d 100644
--- a/src/ringo/molecule/model/atom.rs
+++ b/src/ringo/molecule/model/atom.rs
@@ -1,9 +1,28 @@
 use crate::ringo::molecule::model::element::Element;
 
-#[derive(Hash, Eq, PartialEq)]
+#[derive(Hash, Eq, PartialEq, Debug)]
 pub struct Atom {
     pub element: Element,
     pub isotope: u8,
     pub charge: i8,
     pub hs: u8,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_atom() {
+        let atom = Atom {
+            element: Element { atomic_number: 6 },
+            isotope: 12,
+            charge: 0,
+            hs: 0,
+        };
+        assert_eq!(atom.element, Element { atomic_number: 6 });
+        assert_eq!(atom.isotope, 12);
+        assert_eq!(atom.charge, 0);
+        assert_eq!(atom.hs, 0);
+    }
+}
diff --git a/src/ringo/molecule/model/bond.rs b/src/ringo/molecule/model/bond.rs
index c37646d..3c2a411 100644
--- a/src/ringo/molecule/model/bond.rs
+++ b/src/ringo/molecule/model/bond.rs
@@ -9,3 +9,16 @@ pub enum BondOrder {
 pub struct Bond {
     pub order: BondOrder,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_bond_order() {
+        let bond = Bond {
+            order: BondOrder::Single,
+        };
+        assert_eq!(bond.order, BondOrder::Single);
+    }
+}
diff --git a/src/ringo/molecule/model/element.rs b/src/ringo/molecule/model/element.rs
index 0fc5eea..2607977 100644
--- a/src/ringo/molecule/model/element.rs
+++ b/src/ringo/molecule/model/element.rs
@@ -1,93 +1,106 @@
-#[derive(Hash, Eq, PartialEq)]
+#[derive(Hash, Eq, PartialEq, Debug)]
 pub struct Element {
     pub atomic_number: u8,
 }
 
-pub fn atomic_weight(element: &Element) -> f64 {
-    match element.atomic_number {
-        1 => 1.007825,
-        2 => 4.002603,
-        3 => 6.938,
-        4 => 9.0121831,
-        5 => 10.806,
-        6 => 12.011,
-        7 => 14.007,
-        8 => 15.999,
-        9 => 18.998403163,
-        10 => 20.180,
-        11 => 22.990,
-        12 => 24.305,
-        13 => 26.9815385,
-        14 => 28.085,
-        15 => 30.973761998,
-        16 => 32.06,
-        17 => 35.45,
-        18 => 39.948,
-        19 => 39.0983,
-        20 => 40.078,
-        21 => 44.955908,
-        22 => 47.867,
-        23 => 50.9415,
-        24 => 51.9961,
-        25 => 54.938044,
-        26 => 55.845,
-        27 => 58.933194,
-        28 => 58.6934,
-        29 => 63.546,
-        30 => 65.38,
-        31 => 69.723,
-        32 => 72.630,
-        33 => 74.921595,
-        34 => 78.96,
-        35 => 79.904,
-        36 => 83.798,
-        37 => 85.4678,
-        38 => 87.62,
-        39 => 88.90584,
-        40 => 91.224,
-        41 => 92.90637,
-        42 => 95.95,
-        43 => 98.0,
-        44 => 101.07,
-        45 => 102.90550,
-        46 => 106.42,
-        47 => 107.8682,
-        48 => 112.414,
-        49 => 114.818,
-        50 => 118.710,
-        51 => 121.760,
-        52 => 127.60,
-        53 => 126.90447,
-        54 => 131.293,
-        55 => 132.90545196,
-        56 => 137.327,
-        57 => 138.90547,
-        58 => 140.116,
-        59 => 140.90766,
-        60 => 144.242,
-        61 => 145.0,
-        62 => 150.36,
-        63 => 151.964,
-        64 => 157.25,
-        65 => 158.92535,
-        66 => 162.500,
-        67 => 164.93033,
-        68 => 167.259,
-        69 => 168.93422,
-        70 => 173.054,
-        71 => 174.9668,
-        72 => 178.49,
-        73 => 180.94788,
-        74 => 183.84,
-        75 => 186.207,
-        76 => 190.23,
-        77 => 192.217,
-        78 => 195.084,
-        79 => 196.966569,
-        80 => 200.592,
-        81 => 204.38,
-        82 => 207.2,
-        83 => 208.98040,
-        _ => panic!("Unsupported atomic number {}", element.atomic_number),
+impl Element {
+    pub fn atomic_weight(&self) -> f64 {
+        match self.atomic_number {
+            1 => 1.007825,
+            2 => 4.002603,
+            3 => 6.938,
+            4 => 9.0121831,
+            5 => 10.806,
+            6 => 12.011,
+            7 => 14.007,
+            8 => 15.999,
+            9 => 18.998403163,
+            10 => 20.180,
+            11 => 22.990,
+            12 => 24.305,
+            13 => 26.9815385,
+            14 => 28.085,
+            15 => 30.973761998,
+            16 => 32.06,
+            17 => 35.45,
+            18 => 39.948,
+            19 => 39.0983,
+            20 => 40.078,
+            21 => 44.955908,
+            22 => 47.867,
+            23 => 50.9415,
+            24 => 51.9961,
+            25 => 54.938044,
+            26 => 55.845,
+            27 => 58.933194,
+            28 => 58.6934,
+            29 => 63.546,
+            30 => 65.38,
+            31 => 69.723,
+            32 => 72.630,
+            33 => 74.921595,
+            34 => 78.96,
+            35 => 79.904,
+            36 => 83.798,
+            37 => 85.4678,
+            38 => 87.62,
+            39 => 88.90584,
+            40 => 91.224,
+            41 => 92.90637,
+            42 => 95.95,
+            43 => 98.0,
+            44 => 101.07,
+            45 => 102.90550,
+            46 => 106.42,
+            47 => 107.8682,
+            48 => 112.414,
+            49 => 114.818,
+            50 => 118.710,
+            51 => 121.760,
+            52 => 127.60,
+            53 => 126.90447,
+            54 => 131.293,
+            55 => 132.90545196,
+            56 => 137.327,
+            57 => 138.90547,
+            58 => 140.116,
+            59 => 140.90766,
+            60 => 144.242,
+            61 => 145.0,
+            62 => 150.36,
+            63 => 151.964,
+            64 => 157.25,
+            65 => 158.92535,
+            66 => 162.500,
+            67 => 164.93033,
+            68 => 167.259,
+            69 => 168.93422,
+            70 => 173.054,
+            71 => 174.9668,
+            72 => 178.49,
+            73 => 180.94788,
+            74 => 183.84,
+            75 => 186.207,
+            76 => 190.23,
+            77 => 192.217,
+            78 => 195.084,
+            79 => 196.966569,
+            80 => 200.592,
+            81 => 204.38,
+            82 => 207.2,
+            83 => 208.98040,
+            _ => panic!("Unsupported atomic number {}", self.atomic_number),
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::ringo::molecule::model::element::Element;
+
+    #[test]
+    fn test_element() {
+        let element = Element { atomic_number: 1 };
+        assert_eq!(element.atomic_weight(), 1.007825);
     }
 }
diff --git a/src/ringo/molecule/model/molecule.rs b/src/ringo/molecule/model/molecule.rs
index 2ef01df..354d122 100644
--- a/src/ringo/molecule/model/molecule.rs
+++ b/src/ringo/molecule/model/molecule.rs
@@ -1,9 +1,8 @@
+use crate::ringo::fingerprint::fingerprint::{Fingerprint, FINGERPRINT_SIZE};
 use crate::ringo::math::similarity::tanimoto::tanimoto_bitset;
 use crate::ringo::molecule::model::atom::Atom;
 use crate::ringo::molecule::model::bond::Bond;
-use crate::ringo::molecule::model::element::atomic_weight;
 use crate::ringo::molecule::smiles::reader::molecule::parse_molecule;
-use crate::ringo::ringo::fingerprint::{Fingerprint, FINGERPRINT_SIZE};
 use fixedbitset::FixedBitSet;
 use petgraph::stable_graph::{EdgeIndex, NodeIndex, StableGraph};
 use petgraph::visit::EdgeRef;
@@ -82,7 +81,7 @@ impl Molecule {
     pub fn weight(&self) -> f64 {
         let mut weight: f64 = 0.0;
         for atom in self.graph.node_weights() {
-            weight += atomic_weight(atom.element.borrow())
+            weight += atom.element.atomic_weight();
         }
         weight
     }
diff --git a/src/ringo/ringo.rs b/src/ringo/ringo.rs
index df87b4d..34de02b 100644
--- a/src/ringo/ringo.rs
+++ b/src/ringo/ringo.rs
@@ -1,4 +1,2 @@
-pub(crate) mod fingerprint;
 mod index;
-mod index_item;
 mod search;
diff --git a/src/ringo/ringo/index.rs b/src/ringo/ringo/index.rs
index a06ccc5..3612268 100644
--- a/src/ringo/ringo/index.rs
+++ b/src/ringo/ringo/index.rs
@@ -1,41 +1,3 @@
-use crate::ringo::molecule::smiles::reader::molecule::parse_molecule;
-use crate::ringo::ringo::index_item::IndexItem;
-use std::fs::File;
-use std::io::{BufRead, BufWriter, Write};
-use bincode::{encode_into_slice};
-use crate::ringo::ringo::fingerprint::FINGERPRINT_SIZE;
-
-#[cfg(windows)]
-const LINE_ENDING_LENGTH: usize = 2;
-#[cfg(not(windows))]
-const LINE_ENDING_LENGTH: usize = 1;
-
-fn index(smiles_file: &str) {
-    // open file for reading
-    let fi = File::open(smiles_file).expect("Could not open file");
-
-    // open binary file for index
-    let mut offset = 0;
-    let fo = File::create(smiles_file.to_owned() + ".fp");
-    let mut writer = BufWriter::new(fo.unwrap());
-
-    for line in std::io::BufReader::new(fi).lines() {
-        let line = line.unwrap();
-        let molecule = parse_molecule(&line).unwrap().1;
-        let index_item = IndexItem {
-            position: offset,
-            fingerprint: molecule.ecfp(2, 512),
-        };
-        offset += line.len() + LINE_ENDING_LENGTH;
-
-        let mut buf = vec![0u8; FINGERPRINT_SIZE / 8 + 8];
-
-        encode_into_slice(&index_item, buf.as_mut_slice(), bincode::config::standard()).unwrap();
-        writer.write(&buf).unwrap();
-    }
-}
-
-#[test]
-fn test_index() {
-    index("molecules.smi");
-}
+pub(crate) mod index;
+pub mod index_item;
+mod main;
diff --git a/src/ringo/ringo/index/index.rs b/src/ringo/ringo/index/index.rs
new file mode 100644
index 0000000..55e6419
--- /dev/null
+++ b/src/ringo/ringo/index/index.rs
@@ -0,0 +1,46 @@
+use crate::ringo::fingerprint::fingerprint::FINGERPRINT_SIZE;
+use crate::ringo::molecule::smiles::reader::molecule::parse_molecule;
+use crate::ringo::ringo::index::index_item::IndexItem;
+use bincode::encode_into_slice;
+use std::fs::File;
+use std::io::{BufRead, BufWriter, Write};
+
+#[cfg(windows)]
+const LINE_ENDING_LENGTH: usize = 2;
+#[cfg(not(windows))]
+const LINE_ENDING_LENGTH: usize = 1;
+
+pub(crate) fn index(smiles_file: &str) {
+    // open file for reading
+    let fi = File::open(smiles_file).expect("Could not open file");
+
+    // open binary file for index
+    let mut offset = 0;
+    let fo = File::create(smiles_file.to_owned() + ".fp");
+    let mut writer = BufWriter::new(fo.unwrap());
+
+    for line in std::io::BufReader::new(fi).lines() {
+        let line = line.unwrap();
+        let molecule = parse_molecule(&line).unwrap().1;
+        let index_item = IndexItem {
+            position: offset,
+            fingerprint: molecule.ecfp(2, 512),
+        };
+        offset += line.len() + LINE_ENDING_LENGTH;
+
+        let mut buf = vec![0u8; FINGERPRINT_SIZE / 8 + 8];
+
+        encode_into_slice(&index_item, buf.as_mut_slice(), bincode::config::standard()).unwrap();
+        writer.write(&buf).unwrap();
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::ringo::ringo::index::index::index;
+
+    #[test]
+    fn test_index() {
+        index("molecules.smi");
+    }
+}
diff --git a/src/ringo/ringo/index_item.rs b/src/ringo/ringo/index/index_item.rs
similarity index 83%
rename from src/ringo/ringo/index_item.rs
rename to src/ringo/ringo/index/index_item.rs
index ad33538..74ae080 100644
--- a/src/ringo/ringo/index_item.rs
+++ b/src/ringo/ringo/index/index_item.rs
@@ -1,4 +1,4 @@
-use crate::ringo::ringo::fingerprint::Fingerprint;
+use crate::ringo::fingerprint::fingerprint::Fingerprint;
 use bincode::{Decode, Encode};
 
 #[derive(Debug, Encode, Decode)]
@@ -9,8 +9,8 @@ pub struct IndexItem {
 
 #[cfg(test)]
 mod tests {
-    use crate::ringo::ringo::fingerprint::Fingerprint;
-    use crate::ringo::ringo::index_item::IndexItem;
+    use crate::ringo::fingerprint::fingerprint::Fingerprint;
+    use crate::ringo::ringo::index::index_item::IndexItem;
     use bincode::config::standard;
     use bincode::{decode_from_slice, encode_to_vec};
     use fixedbitset::FixedBitSet;
diff --git a/src/ringo/ringo/index/main.rs b/src/ringo/ringo/index/main.rs
new file mode 100644
index 0000000..4f841dd
--- /dev/null
+++ b/src/ringo/ringo/index/main.rs
@@ -0,0 +1,3 @@
+fn main() {
+    println!("ringo-index");
+}
diff --git a/src/ringo/ringo/search.rs b/src/ringo/ringo/search.rs
index ddc8b65..c6075b6 100644
--- a/src/ringo/ringo/search.rs
+++ b/src/ringo/ringo/search.rs
@@ -1,71 +1,2 @@
-use std::fs::File;
-use std::io::{BufRead, BufReader, Read, Seek};
-use crate::ringo::math::similarity::tanimoto::tanimoto_bitset;
-use crate::ringo::molecule::smiles::reader::molecule::parse_molecule;
-use crate::ringo::ringo::index_item::IndexItem;
-
-pub struct SearchResult {
-    pub line: String,
-    pub similarity: f32
-}
-
-pub fn similarity_search(smiles_file: &str, query: &str, min_similarity: f32, limit: usize) -> Vec<SearchResult> {
-    let query = parse_molecule(query).unwrap().1;
-    let query_fp = query.ecfp(2, 512);
-
-    // smiles file
-    let fis = File::open(&smiles_file).expect("Could not open file");
-    let mut reader = BufReader::new(fis);
-
-    //fingerprings file
-    let fif = File::open(smiles_file.to_owned() + ".fp").expect("Could not open file");
-    let file_len = fif.metadata().unwrap().len();
-    let index_item_size = 72u8;
-    let index_count = file_len / index_item_size as u64;
-    let mut buf_reader = BufReader::new(fif);
-
-    let mut results = Vec::new();
-
-    for _ in 0..index_count {
-        // read index item from file
-        let mut buf = vec![0u8; index_item_size as usize];
-        buf_reader.read_exact(&mut buf).unwrap();
-
-        // decode index item
-        let index_item: IndexItem = bincode::decode_from_slice(&buf, bincode::config::standard()).unwrap().0;
-
-        // calculate similarity
-        let similarity = tanimoto_bitset(&index_item.fingerprint.0, &query_fp.0);
-
-        // print similarity if it is greater than min_similarity
-        if similarity >= min_similarity {
-            let position  = index_item.position;
-            reader.seek(std::io::SeekFrom::Start(position as u64)).unwrap();
-
-            let mut line = String::new();
-            reader.read_line(&mut line).unwrap();
-            // println!("{i} {similarity} {position} {line}");
-            results.push(SearchResult {
-                line: line,
-                similarity: similarity
-            });
-
-            if results.len() >= limit {
-                break;
-            }
-        }
-    }
-
-    results
-}
-
-#[test]
-fn test_similarity_search() {
-    let results = similarity_search("molecules.smi", "CC(C)CC1=CC=C(C=C1)C(C)C(=O)O", 0.7, 100);
-    assert_eq!(results.len(), 1);
-    assert!(results[0].line.starts_with("CC(C)CC1=CC=C(C=C1)C(C)C(=O)O"));
-    assert_eq!(results[0].similarity, 1.0);
-    let results = similarity_search("molecules.smi", "CC(C)CC1=CC=C(C=C1)C(C)C(=O)O", 0.5, 100);
-    assert_eq!(results.len(), 2);
-
-}
+mod main;
+pub mod search;
diff --git a/src/ringo/ringo/search/main.rs b/src/ringo/ringo/search/main.rs
new file mode 100644
index 0000000..1c46ffe
--- /dev/null
+++ b/src/ringo/ringo/search/main.rs
@@ -0,0 +1,3 @@
+fn main() {
+    println!("ringo-search");
+}
diff --git a/src/ringo/ringo/search/search.rs b/src/ringo/ringo/search/search.rs
new file mode 100644
index 0000000..2179248
--- /dev/null
+++ b/src/ringo/ringo/search/search.rs
@@ -0,0 +1,86 @@
+use crate::ringo::math::similarity::tanimoto::tanimoto_bitset;
+use crate::ringo::molecule::smiles::reader::molecule::parse_molecule;
+use crate::ringo::ringo::index::index_item::IndexItem;
+use std::fs::File;
+use std::io::{BufRead, BufReader, Read, Seek};
+
+pub struct SearchResult {
+    pub line: String,
+    pub similarity: f32,
+}
+
+pub fn similarity_search(
+    smiles_file: &str,
+    query: &str,
+    min_similarity: f32,
+    limit: usize,
+) -> Vec<SearchResult> {
+    let query = parse_molecule(query).unwrap().1;
+    let query_fp = query.ecfp(2, 512);
+
+    // smiles file
+    let fis = File::open(&smiles_file).expect("Could not open file");
+    let mut reader = BufReader::new(fis);
+
+    //fingerprings file
+    let fif = File::open(smiles_file.to_owned() + ".fp").expect("Could not open file");
+    let file_len = fif.metadata().unwrap().len();
+    let index_item_size = 72u8;
+    let index_count = file_len / index_item_size as u64;
+    let mut buf_reader = BufReader::new(fif);
+
+    let mut results = Vec::new();
+
+    for _ in 0..index_count {
+        // read index item from file
+        let mut buf = vec![0u8; index_item_size as usize];
+        buf_reader.read_exact(&mut buf).unwrap();
+
+        // decode index item
+        let index_item: IndexItem = bincode::decode_from_slice(&buf, bincode::config::standard())
+            .unwrap()
+            .0;
+
+        // calculate similarity
+        let similarity = tanimoto_bitset(&index_item.fingerprint.0, &query_fp.0);
+
+        // print similarity if it is greater than min_similarity
+        if similarity >= min_similarity {
+            let position = index_item.position;
+            reader
+                .seek(std::io::SeekFrom::Start(position as u64))
+                .unwrap();
+
+            let mut line = String::new();
+            reader.read_line(&mut line).unwrap();
+            // println!("{i} {similarity} {position} {line}");
+            results.push(SearchResult {
+                line: line,
+                similarity: similarity,
+            });
+
+            if results.len() >= limit {
+                break;
+            }
+        }
+    }
+
+    results
+}
+
+#[cfg(test)]
+mod test {
+    use crate::ringo::ringo::index::index::index;
+    use crate::ringo::ringo::search::search::similarity_search;
+
+    #[test]
+    fn test_similarity_search() {
+        index("molecles.smi");
+        let results = similarity_search("molecules.smi", "CC(C)CC1=CC=C(C=C1)C(C)C(=O)O", 0.7, 100);
+        assert_eq!(results.len(), 1);
+        assert!(results[0].line.starts_with("CC(C)CC1=CC=C(C=C1)C(C)C(=O)O"));
+        assert_eq!(results[0].similarity, 1.0);
+        let results = similarity_search("molecules.smi", "CC(C)CC1=CC=C(C=C1)C(C)C(=O)O", 0.5, 100);
+        assert_eq!(results.len(), 2);
+    }
+}