diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..161a60f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.DS_Store
+build
+.VSCodeCounter
+plutus.json
diff --git a/README.md b/README.md
index 9e34bea..b56b059 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,13 @@
-# aiken-linked-list
\ No newline at end of file
+# aiken-linked-list
+
+## Building
+
+```sh
+aiken build
+```
+
+To run all tests, simply do:
+
+```sh
+aiken check
+```
diff --git a/aiken.lock b/aiken.lock
new file mode 100644
index 0000000..0a72eb3
--- /dev/null
+++ b/aiken.lock
@@ -0,0 +1,15 @@
+# This file was generated by Aiken
+# You typically do not need to edit this file
+
+[[requirements]]
+name = "aiken-lang/stdlib"
+version = "1.7.0"
+source = "github"
+
+[[packages]]
+name = "aiken-lang/stdlib"
+version = "1.7.0"
+requirements = []
+source = "github"
+
+[etags]
diff --git a/aiken.toml b/aiken.toml
new file mode 100644
index 0000000..f82ae48
--- /dev/null
+++ b/aiken.toml
@@ -0,0 +1,14 @@
+name = "aiken-lang/aiken-linked-list"
+version = "0.0.0"
+license = "Apache-2.0"
+description = "Aiken contracts for project 'aiken-lang/aiken-linked-list'"
+
+[repository]
+user = "aiken-lang"
+project = "aiken-linked-list"
+platform = "github"
+
+[[dependencies]]
+name = "aiken-lang/stdlib"
+version = "1.7.0"
+source = "github"
diff --git a/lib/linkedlist/constants.ak b/lib/linkedlist/constants.ak
new file mode 100644
index 0000000..32b2f1f
--- /dev/null
+++ b/lib/linkedlist/constants.ak
@@ -0,0 +1 @@
+pub const origin_node_token_name = "FSN"
diff --git a/lib/linkedlist/linked_list.ak b/lib/linkedlist/linked_list.ak
new file mode 100644
index 0000000..029d351
--- /dev/null
+++ b/lib/linkedlist/linked_list.ak
@@ -0,0 +1,110 @@
+use aiken/bytearray
+use aiken/interval
+use aiken/list
+use aiken/transaction.{Output}
+use aiken/transaction/value.{lovelace_of}
+use linkedlist/constants
+use linkedlist/types.{Common, Config, POSIXTime, PubKeyHash, SetNode}
+use linkedlist/utils
+
+pub fn init(common: Common) -> Bool {
+  let must_spend_nodes = list.length(common.node_inputs) > 0
+  let must_exactly_one_node_outputs = list.length(common.node_outputs) == 1
+  let must_mint_correctly =
+    utils.validate_mint(
+      common.mint,
+      common.own_cs,
+      constants.origin_node_token_name,
+      1,
+    )
+  must_spend_nodes? && must_exactly_one_node_outputs? && must_mint_correctly?
+}
+
+pub fn deinit(common: Common) -> Bool {
+  let must_spend_exactly_one_node_input = list.length(common.node_inputs) == 1
+  let must_not_produce_node_output = list.length(common.node_outputs) == 0
+  let must_burn_correctly =
+    utils.validate_mint(
+      common.mint,
+      common.own_cs,
+      constants.origin_node_token_name,
+      -1,
+    )
+  must_spend_exactly_one_node_input? && must_not_produce_node_output? && must_burn_correctly?
+}
+
+pub fn insert(common: Common, insert_key: PubKeyHash, node: SetNode) -> Bool {
+  let must_cover_inserting_key = utils.cover_key(node, insert_key)
+  expect [covering_node] = common.node_inputs
+  let prev_node_datum = utils.as_predecessor_of(node, insert_key)
+  let node_datum = utils.as_successor_of(insert_key, node)
+  let must_has_datum_in_output =
+    list.any(
+      common.node_outputs,
+      fn(node_pair) { node_datum == node_pair.node },
+    )
+  let must_correct_node_output =
+    list.any(
+      common.node_outputs,
+      fn(node_pair) {
+        covering_node.val == node_pair.val && prev_node_datum == node_pair.node
+      },
+    )
+
+  let must_mint_correct =
+    utils.validate_mint(
+      common.mint,
+      common.own_cs,
+      bytearray.concat(constants.origin_node_token_name, insert_key),
+      1,
+    )
+  must_cover_inserting_key? && must_has_datum_in_output? && must_correct_node_output? && must_mint_correct?
+}
+
+pub fn remove(
+  common: Common,
+  range: POSIXTime,
+  disc_config: Config,
+  outs: List<Output>,
+  sigs: List<PubKeyHash>,
+  remove_key: PubKeyHash,
+  node: SetNode,
+) -> Bool {
+  let must_cover_remove_key = utils.cover_key(node, remove_key)
+  let prev_node_datum = utils.as_predecessor_of(node, remove_key)
+  let node_datum = utils.as_successor_of(remove_key, node)
+  let must_spend_two_nodes = list.length(common.node_inputs) == 2
+  expect Some(stay_node) =
+    list.find(common.node_inputs, fn(input) { prev_node_datum == input.node })
+  expect Some(remove_node) =
+    list.find(common.node_inputs, fn(input) { node_datum == input.node })
+  let remove_token_name =
+    bytearray.concat(constants.origin_node_token_name, remove_key)
+  let must_correct_node_output =
+    list.any(
+      common.node_outputs,
+      fn(node_pair) { stay_node.val == node_pair.val && node == node_pair.node },
+    )
+  let must_mint_correct =
+    utils.validate_mint(common.mint, common.own_cs, remove_token_name, -1)
+  let must_sign_by_user = list.has(sigs, remove_key)
+  let own_input_lovelace = lovelace_of(remove_node.val)
+  let own_input_fee = utils.div_ceil(own_input_lovelace, 4)
+  let disc_deadline = disc_config.deadline
+  let must_satisfy_removal_broke_phase_rules =
+    if
+    interval.is_entirely_after(interval.after(disc_deadline - 8_640_000), range){
+    
+      True
+    } else {
+      list.any(
+        outs,
+        fn(out) {
+          out.address == disc_config.penalty_address && own_input_fee < lovelace_of(
+            out.value,
+          )
+        },
+      )
+    }
+  must_cover_remove_key? && must_spend_two_nodes? && must_correct_node_output? && must_mint_correct? && must_sign_by_user? && must_satisfy_removal_broke_phase_rules?
+}
diff --git a/lib/linkedlist/types.ak b/lib/linkedlist/types.ak
new file mode 100644
index 0000000..0b92a87
--- /dev/null
+++ b/lib/linkedlist/types.ak
@@ -0,0 +1,51 @@
+use aiken/hash.{Blake2b_224, Hash}
+use aiken/transaction.{OutputReference}
+use aiken/transaction/credential.{Address, VerificationKey}
+use aiken/transaction/value.{AssetName, PolicyId, Value}
+
+/// A number of milliseconds since 00:00:00 UTC on 1 January 1970.
+pub type POSIXTime =
+  Int
+
+pub type AssetClass {
+  policy_id: PolicyId,
+  asset_name: AssetName,
+}
+
+pub type PubKeyHash =
+  Hash<Blake2b_224, VerificationKey>
+
+pub type Config {
+  init_utxo: OutputReference,
+  deadline: POSIXTime,
+  penalty_address: Address,
+}
+
+pub type NodeKey {
+  Key { key: PubKeyHash }
+  Empty
+}
+
+pub type SetNode {
+  key: NodeKey,
+  next: NodeKey,
+}
+
+pub type NodePair {
+  val: Value,
+  node: SetNode,
+}
+
+pub type Common {
+  own_cs: PolicyId,
+  mint: Value,
+  node_inputs: List<NodePair>,
+  node_outputs: List<NodePair>,
+}
+
+pub type NodeAction {
+  Init
+  Deinit
+  Insert
+  Remove
+}
diff --git a/lib/linkedlist/utils.ak b/lib/linkedlist/utils.ak
new file mode 100644
index 0000000..cae5eca
--- /dev/null
+++ b/lib/linkedlist/utils.ak
@@ -0,0 +1,45 @@
+use aiken/bytearray
+use aiken/dict
+use aiken/transaction/value.{Value}
+use linkedlist/types.{Empty, Key, PubKeyHash, SetNode}
+
+pub fn validate_mint(
+  mints: Value,
+  expected_minting_policy: ByteArray,
+  expected_minting_name: ByteArray,
+  expected_minting_amt: Int,
+) -> Bool {
+  let mints_policy = dict.to_list(value.tokens(mints, expected_minting_policy))
+  mints_policy == [(expected_minting_name, expected_minting_amt)]
+}
+
+pub fn cover_key(node: SetNode, insert_key: PubKeyHash) -> Bool {
+  let less_than_key =
+    when node.key is {
+      Empty -> True
+      Key(key) -> bytearray.compare(key, insert_key) == Less
+    }
+  let more_than_key =
+    when node.next is {
+      Empty -> True
+      Key(key) -> bytearray.compare(key, insert_key) == Greater
+    }
+  less_than_key? && more_than_key?
+}
+
+pub fn as_predecessor_of(node: SetNode, next_key: PubKeyHash) -> SetNode {
+  SetNode { key: node.key, next: Key(next_key) }
+}
+
+pub fn as_successor_of(prev_key: PubKeyHash, node: SetNode) -> SetNode {
+  SetNode { key: Key(prev_key), next: node.next }
+}
+
+pub fn div_ceil(a, b: Int) -> Int {
+  let div = a / b
+  let rem = a % b
+  when rem is {
+    0 -> div
+    _ -> div + 1
+  }
+}