diff --git a/packages/rs-dpp/src/data_contract/associated_token/token_perpetual_distribution/distribution_function/mod.rs b/packages/rs-dpp/src/data_contract/associated_token/token_perpetual_distribution/distribution_function/mod.rs
index 432adc7b6cb..a8ed4f6d5a8 100644
--- a/packages/rs-dpp/src/data_contract/associated_token/token_perpetual_distribution/distribution_function/mod.rs
+++ b/packages/rs-dpp/src/data_contract/associated_token/token_perpetual_distribution/distribution_function/mod.rs
@@ -159,7 +159,9 @@ pub enum DistributionFunction {
     ///
     /// # Example
     /// - Emit 100 tokens per block for the first 1,000 blocks, then 50 tokens per block thereafter.
-    Stepwise(BTreeMap<u64, TokenAmount>),
+    Stepwise(
+        #[serde(deserialize_with = "deserialize_u64_token_amount_map")] BTreeMap<u64, TokenAmount>,
+    ),
 
     /// Emits tokens following a linear function that can increase or decrease over time
     /// with fractional precision.
@@ -558,6 +560,45 @@ pub enum DistributionFunction {
     },
 }
 
+// Custom deserializer helper that accepts both key shapes for JSON and other serde formats:
+// - BTreeMap<u64, TokenAmount>                // numeric timestamp/step keys
+// - BTreeMap<String, TokenAmount>             // numeric-looking strings as keys
+// The function normalizes both into `BTreeMap<u64, TokenAmount>`. If a string key
+// cannot be parsed as `u64`, deserialization fails with a serde error.
+use serde::de::Deserializer;
+fn deserialize_u64_token_amount_map<'de, D>(
+    deserializer: D,
+) -> Result<BTreeMap<u64, TokenAmount>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    // Untagged enum tries variants in order: attempt numeric keys first,
+    // then fallback to string keys.
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    enum U64OrStrMap<V> {
+        // JSON: { 0: 100, 10: 50 }
+        U64(BTreeMap<u64, V>),
+        // JSON: { "0": 100, "10": 50 }
+        Str(BTreeMap<String, V>),
+    }
+
+    let helper: U64OrStrMap<TokenAmount> = U64OrStrMap::deserialize(deserializer)?;
+    match helper {
+        // Already numeric keys; return as-is
+        U64OrStrMap::U64(m) => Ok(m),
+        // Parse numeric-looking string keys into u64, preserving values
+        U64OrStrMap::Str(sm) => sm
+            .into_iter()
+            .map(|(k, v)| {
+                k.parse::<u64>()
+                    .map_err(serde::de::Error::custom)
+                    .map(|kk| (kk, v))
+            })
+            .collect(),
+    }
+}
+
 impl fmt::Display for DistributionFunction {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
diff --git a/packages/rs-dpp/src/data_contract/associated_token/token_pre_programmed_distribution/v0/mod.rs b/packages/rs-dpp/src/data_contract/associated_token/token_pre_programmed_distribution/v0/mod.rs
index b70a4a20ee6..427b9928a53 100644
--- a/packages/rs-dpp/src/data_contract/associated_token/token_pre_programmed_distribution/v0/mod.rs
+++ b/packages/rs-dpp/src/data_contract/associated_token/token_pre_programmed_distribution/v0/mod.rs
@@ -10,6 +10,7 @@ use std::fmt;
 #[derive(Serialize, Deserialize, Decode, Encode, Debug, Clone, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct TokenPreProgrammedDistributionV0 {
+    #[serde(deserialize_with = "deserialize_ts_to_id_amount_map")]
     pub distributions: BTreeMap<TimestampMillis, BTreeMap<Identifier, TokenAmount>>,
 }
 
@@ -26,3 +27,46 @@ impl fmt::Display for TokenPreProgrammedDistributionV0 {
         write!(f, "}}")
     }
 }
+
+use serde::de::Deserializer;
+
+// Custom deserializer for `distributions` that tolerates two JSON shapes:
+// - a map keyed by timestamp millis as numbers (u64)
+// - a map keyed by timestamp millis as strings (e.g. "1735689600000")
+// It normalizes both into `BTreeMap<u64, V>` where V is the inner value map
+// (`BTreeMap<Identifier, TokenAmount>` here). If a string key cannot be parsed
+// as `u64`, deserialization fails with a serde error. Using `BTreeMap` keeps
+// keys ordered by timestamp.
+fn deserialize_ts_to_id_amount_map<'de, D>(
+    deserializer: D,
+) -> Result<BTreeMap<TimestampMillis, BTreeMap<Identifier, TokenAmount>>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    // Untagged enum attempts the variants in order: first try a map with u64
+    // keys; if that doesn't match, try a map with string keys.
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    enum U64OrStrTs<V> {
+        // JSON: { 1735689600000: { <id>: <amount>, ... }, ... }
+        U64(BTreeMap<TimestampMillis, V>),
+        // JSON: { "1735689600000": { <id>: <amount>, ... }, ... }
+        Str(BTreeMap<String, V>),
+    }
+
+    let helper: U64OrStrTs<BTreeMap<Identifier, TokenAmount>> =
+        U64OrStrTs::deserialize(deserializer)?;
+    match helper {
+        // Already has numeric timestamp keys; return as-is
+        U64OrStrTs::U64(m) => Ok(m),
+        // Convert string timestamp keys into u64, preserving values unchanged
+        U64OrStrTs::Str(sm) => sm
+            .into_iter()
+            .map(|(k, v)| {
+                k.parse::<u64>()
+                    .map_err(serde::de::Error::custom)
+                    .map(|ts| (ts, v))
+            })
+            .collect(),
+    }
+}
diff --git a/packages/rs-dpp/src/data_contract/conversion/json/mod.rs b/packages/rs-dpp/src/data_contract/conversion/json/mod.rs
index 2e4147653cc..8a85936b023 100644
--- a/packages/rs-dpp/src/data_contract/conversion/json/mod.rs
+++ b/packages/rs-dpp/src/data_contract/conversion/json/mod.rs
@@ -52,3 +52,296 @@ impl DataContractJsonConversionMethodsV0 for DataContract {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::data_contract::conversion::json::DataContractJsonConversionMethodsV0;
+    use crate::prelude::DataContract;
+    use crate::version::PlatformVersion;
+    use serde_json::json;
+
+    #[test]
+    fn from_json_accepts_stepwise_with_string_keys() {
+        let platform_version = PlatformVersion::latest();
+
+        let owner = "HtQNfXBZJu3WnvjvCFJKgbvfgWYJxWxaFWy23TKoFjg9";
+        let id = "BmKTJeLL3GfH8FxEx7SUbTog4eAKj8vJRDi97gYkxB9p";
+
+        let contract = json!({
+            "$format_version": "1",
+            "id": id,
+            "ownerId": owner,
+            "version": 1,
+            "config": {
+                "$format_version": "0",
+                "canBeDeleted": false,
+                "readonly": false,
+                "keepsHistory": false,
+                "documentsKeepHistoryContractDefault": false,
+                "documentsMutableContractDefault": true,
+                "documentsCanBeDeletedContractDefault": false,
+                "requiresIdentityEncryptionBoundedKey": null,
+                "requiresIdentityDecryptionBoundedKey": null
+            },
+            "documentSchemas": {},
+            "tokens": {
+                "0": {
+                    "$format_version": "0",
+                    "conventions": { "$format_version": "0", "decimals": 2, "localizations": {} },
+                    "distributionRules": {
+                        "$format_version": "0",
+                        "perpetualDistribution": {
+                            "$format_version": "0",
+                            "distributionType": {
+                                "BlockBasedDistribution": {
+                                    "interval": 10,
+                                    "function": {
+                                        "Stepwise": { "0": 100, "10": 50 }
+                                    }
+                                }
+                            },
+                            "distributionRecipient": "ContractOwner"
+                        },
+                        "perpetualDistributionRules": {"V0": {
+                            "authorized_to_make_change": "ContractOwner",
+                            "admin_action_takers": "ContractOwner",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "preProgrammedDistribution": null,
+                        "preProgrammedDistributionRules": {"V0": {
+                            "authorized_to_make_change": "NoOne",
+                            "admin_action_takers": "NoOne",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "newTokensDestinationIdentity": null,
+                        "newTokensDestinationIdentityRules": {"V0": {
+                            "authorized_to_make_change": "ContractOwner",
+                            "admin_action_takers": "ContractOwner",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "mintingAllowChoosingDestination": false,
+                        "mintingAllowChoosingDestinationRules": {"V0": {
+                            "authorized_to_make_change": "ContractOwner",
+                            "admin_action_takers": "ContractOwner",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "changeDirectPurchasePricingRules": {"V0": {
+                            "authorized_to_make_change": "NoOne",
+                            "admin_action_takers": "NoOne",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }}
+                    },
+                    "marketplaceRules": {"$format_version": "0", "tradeMode": "NotTradeable"},
+                    "manualMintingRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "manualBurningRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "freezeRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "unfreezeRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "destroyFrozenFundsRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "emergencyActionRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "directPurchaseRules": {"V0": {
+                        "authorized_to_make_change": "NoOne",
+                        "admin_action_takers": "NoOne",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "mainControlGroup": null,
+                    "mainControlGroupCanBeModified": "NoOne"
+                }
+            }
+        });
+
+        let result = DataContract::from_json(contract, true, &platform_version);
+        assert!(
+            result.is_ok(),
+            "Stepwise with string keys should be accepted by from_json"
+        );
+    }
+
+    #[test]
+    fn from_json_accepts_preprogrammed_with_string_timestamp_keys() {
+        let platform_version = PlatformVersion::latest();
+
+        let owner = "HtQNfXBZJu3WnvjvCFJKgbvfgWYJxWxaFWy23TKoFjg9";
+        let id = "BmKTJeLL3GfH8FxEx7SUbTog4eAKj8vJRDi97gYkxB9p";
+
+        let contract = json!({
+            "$format_version": "1",
+            "id": id,
+            "ownerId": owner,
+            "version": 1,
+            "config": {
+                "$format_version": "0",
+                "canBeDeleted": false,
+                "readonly": false,
+                "keepsHistory": false,
+                "documentsKeepHistoryContractDefault": false,
+                "documentsMutableContractDefault": true,
+                "documentsCanBeDeletedContractDefault": false,
+                "requiresIdentityEncryptionBoundedKey": null,
+                "requiresIdentityDecryptionBoundedKey": null
+            },
+            "documentSchemas": {},
+            "tokens": {
+                "0": {
+                    "$format_version": "0",
+                    "conventions": { "$format_version": "0", "decimals": 2, "localizations": {} },
+                    "distributionRules": {
+                        "$format_version": "0",
+                        "perpetualDistribution": null,
+                        "perpetualDistributionRules": {"V0": {
+                            "authorized_to_make_change": "NoOne",
+                            "admin_action_takers": "NoOne",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "preProgrammedDistribution": {
+                            "$format_version": "0",
+                            "distributions": {
+                                "1735689600000": {
+                                    "HtQNfXBZJu3WnvjvCFJKgbvfgWYJxWxaFWy23TKoFjg9": 1000
+                                }
+                            }
+                        },
+                        "preProgrammedDistributionRules": {"V0": {
+                            "authorized_to_make_change": "ContractOwner",
+                            "admin_action_takers": "ContractOwner",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "newTokensDestinationIdentity": null,
+                        "newTokensDestinationIdentityRules": {"V0": {
+                            "authorized_to_make_change": "ContractOwner",
+                            "admin_action_takers": "ContractOwner",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "mintingAllowChoosingDestination": false,
+                        "mintingAllowChoosingDestinationRules": {"V0": {
+                            "authorized_to_make_change": "ContractOwner",
+                            "admin_action_takers": "ContractOwner",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }},
+                        "changeDirectPurchasePricingRules": {"V0": {
+                            "authorized_to_make_change": "NoOne",
+                            "admin_action_takers": "NoOne",
+                            "changing_authorized_action_takers_to_no_one_allowed": false,
+                            "changing_admin_action_takers_to_no_one_allowed": false,
+                            "self_changing_admin_action_takers_allowed": false
+                        }}
+                    },
+                    "marketplaceRules": {"$format_version": "0", "tradeMode": "NotTradeable"},
+                    "manualMintingRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "manualBurningRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "freezeRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "unfreezeRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "destroyFrozenFundsRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "emergencyActionRules": {"V0": {
+                        "authorized_to_make_change": "ContractOwner",
+                        "admin_action_takers": "ContractOwner",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "directPurchaseRules": {"V0": {
+                        "authorized_to_make_change": "NoOne",
+                        "admin_action_takers": "NoOne",
+                        "changing_authorized_action_takers_to_no_one_allowed": false,
+                        "changing_admin_action_takers_to_no_one_allowed": false,
+                        "self_changing_admin_action_takers_allowed": false
+                    }},
+                    "mainControlGroup": null,
+                    "mainControlGroupCanBeModified": "NoOne"
+                }
+            }
+        });
+
+        let result = DataContract::from_json(contract, true, &platform_version);
+        assert!(
+            result.is_ok(),
+            "PreProgrammed with string timestamp keys should be accepted by from_json"
+        );
+    }
+}