diff --git a/proof-data-provider/methods.js b/proof-data-provider/methods.js
index 36384a0..3674537 100644
--- a/proof-data-provider/methods.js
+++ b/proof-data-provider/methods.js
@@ -885,70 +885,6 @@ async function checkParamsUtype2(params) {
 
 inputErrors.utype2 = checkParamsUtype2;
 
-// Function for checking input params for method getProofByKey
-async function checkParamsGp1(params) {
-  const result = {
-    error: false,
-    message: null
-  };
-  // check if the params have only two keys
-  if (Object.keys(params).length > 2) {
-    result.error = true;
-    result.message =
-      'Object "params" should have only two properties - "index" and "key".';
-    return result;
-  }
-  // check if the keys of params are index and key (can be improved with more detailed messages)
-  if (
-    !Object.prototype.hasOwnProperty.call(params, "index") ||
-    !Object.prototype.hasOwnProperty.call(params, "key")
-  ) {
-    result.error = true;
-    result.message =
-      'There is no required properties "index" and/or "key" in object "params".';
-    return result;
-  }
-  // check data types of params keys
-  if (typeof params.index !== "number" || typeof params.key !== "string") {
-    if (typeof params.index === "number") {
-      result.error = true;
-      result.message = 'Invalid data type of "key". Must be a string.';
-      return result;
-    }
-    result.error = true;
-    result.message = 'Invalid data type of "index". Must be a number.';
-    return result;
-  }
-  // check if the item by input's index exist
-  const item = await managerDB.getItemByIndex(params.index);
-  if (!item) {
-    result.error = true;
-    result.message = `Invalid index. There is no tree with such ${params.index} index.`;
-    return result;
-  }
-
-  // check key value
-  const { depth } = item;
-  const maxnumber = BigInt(2 ** depth) - BigInt(1);
-
-  let bN;
-  try {
-    bN = BigInt(params.key);
-  } catch (e) {
-    result.error = true;
-    result.message = `This "${params.key}" key is not a number.`;
-    return result;
-  }
-  if (bN > maxnumber) {
-    result.error = true;
-    result.message = `This "${params.key}" key is out of range of the tree's depth.`;
-    return result;
-  }
-  return result;
-}
-
-inputErrors.gp1 = checkParamsGp1;
-
 // Function for checking params for method getProofByKeys
 async function checkParamsGp2(params) {
   const result = {
diff --git a/proof-data-provider/methods/getProofByKey.js b/proof-data-provider/methods/getProofByKey.js
new file mode 100644
index 0000000..a89bcc4
--- /dev/null
+++ b/proof-data-provider/methods/getProofByKey.js
@@ -0,0 +1,62 @@
+const SmtLib = require("../helpers/SmtLib.js");
+const managerDB = require("../db.js");
+const { paramsSchema, validate, error } = require("./utils");
+
+const schema = paramsSchema("getProofByKey", {
+  index: { type: "number", required: true },
+  key: { type: "string", required: true }
+});
+
+/**
+ *  Option1. Function for getting one proof for one key.
+ *  @function getProofByKey
+ *  @param {Object} [params] Parameters from the request that was send by client(user)
+ *  @param {Number} [params.index] The index of the existing item (tree), that user got when created a tree into provider's database.
+ *  @param {String} [params.key] The sparse merkle tree's key(path) that proof is required.
+ *  Key must be a number in a range of depth's amount of bits.
+ *  @return {String} Returns a proof for the key in input as the result.
+ */
+// Example:
+/*
+let params = {
+  index: 1575009568558,
+  key : "0x77111aaabbbcccdddeeeeffff000002222233333"
+}
+*/
+const handler = async params => {
+  const validationError = validate(schema, params);
+  if (validationError) return validationError;
+
+  const item = await managerDB.getItemByIndex(params.index);
+  if (!item) {
+    return error(
+      `Invalid index. There is no tree with such ${params.index} index.`
+    );
+  }
+
+  // check key value
+  const { depth } = item;
+  const maxnumber = BigInt(2 ** depth) - BigInt(1);
+
+  let bN;
+  try {
+    bN = BigInt(params.key);
+  } catch (e) {
+    return error(`This "${params.key}" key is not a number.`);
+  }
+
+  if (bN > maxnumber) {
+    return error(
+      `This "${params.key}" key is out of range of the tree's depth.`
+    );
+  }
+
+  if (item.config) {
+    await autoUpdate(params.index);
+  }
+  const tree = new SmtLib(item.depth, item.leaves);
+  const proof = tree.createMerkleProof(params.key);
+  return proof;
+};
+
+module.exports = handler;
diff --git a/proof-data-provider/methods/utils.js b/proof-data-provider/methods/utils.js
new file mode 100644
index 0000000..9842d3a
--- /dev/null
+++ b/proof-data-provider/methods/utils.js
@@ -0,0 +1,33 @@
+const Validator = require("jsonschema").Validator;
+const validator = new Validator();
+
+const paramsSchema = (name, properties) => {
+  const paramsSchemaId = `/${name}Params`;
+  const paramsSchema = {
+    id: paramsSchemaId,
+    type: "object",
+    properties: properties
+  };
+  return paramsSchema;
+};
+
+const error = (message) => ({
+  code: -32602,
+  message: "Invalid params",
+  data: message,
+});
+
+const validate = (schema, params) => {
+  const res = validator.validate(params, schema);
+  if (res.valid) return;
+
+  return {
+    code: -32602,
+    message: "Invalid params",
+    data: res.errors.map(
+      e => `parameter '${e.property.replace("instance.", "")}' ${e.message}`
+    )
+  };
+};
+
+module.exports = { validate, error, paramsSchema };
\ No newline at end of file
diff --git a/proof-data-provider/package.json b/proof-data-provider/package.json
index 0a7461e..c421dc0 100644
--- a/proof-data-provider/package.json
+++ b/proof-data-provider/package.json
@@ -30,6 +30,7 @@
     "ethereumjs-util": "^6.2.0",
     "jayson": "^3.2.0",
     "jsbi": "^3.1.1",
+    "jsonschema": "^1.2.5",
     "web3": "^1.2.4"
   },
   "devDependencies": {
diff --git a/proof-data-provider/server.js b/proof-data-provider/server.js
index b0d50e6..656c134 100644
--- a/proof-data-provider/server.js
+++ b/proof-data-provider/server.js
@@ -3,137 +3,31 @@ const config = require("config");
 const jayson = require("jayson/promise");
 const { errorHandler, methodHandler } = require("./handler_jayson");
 
-const server = jayson.server({
-  addTreeManually: params => {
-    const error = errorHandler("ctype1", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("addTreeManually", params);
-        resolve(result);
-      });
-    });
-  },
-
-  addTreeFromContract: params => {
-    const error = errorHandler("ctype2", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          // server.error just returns {code: 32602, message: 'Internal error', data: 'specific input error'}
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("addTreeFromContract", params);
-        resolve(result);
-      });
-    });
-  },
-  updateTreeManually: params => {
-    const error = errorHandler("utype1", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("updateTreeManually", params);
-        resolve(result);
-      });
-    });
-  },
+const checkAndCall = (methodName, errorHandlerName, params) => {
+  const error = errorHandler(errorHandlerName, params);
+  return error.then(err => {
+    if (err != null) {
+      return Promise.reject(server.error(err.code, err.message, err.data));
+    }
+    return Promise.resolve(methodHandler(methodName, params));
+  });
+};
 
-  extraUpdateTreeFromContract: params => {
-    const error = errorHandler("utype2", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("extraUpdateTreeFromContract", params);
-        resolve(result);
-      });
-    });
-  },
-
-  getProofByKey: params => {
-    const error = errorHandler("gp1", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("getProofByKey", params);
-        resolve(result);
-      });
-    });
-  },
-  getProofByKeys: params => {
-    const error = errorHandler("gp2", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("getProofByKeys", params);
-        resolve(result);
-      });
-    });
-  },
-  getProofByKeyWithCondition: params => {
-    const error = errorHandler("gp3", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("getProofByKeyWithCondition", params);
-        resolve(result);
-      });
-    });
-  },
-  getProofByKeysWithCondition: params => {
-    const error = errorHandler("gp4", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("getProofByKeysWithCondition", params);
-        resolve(result);
-      });
-    });
-  },
-  getRoot: params => {
-    const error = errorHandler("gR", params);
-    return error.then(err => {
-      if (err != null) {
-        return new Promise((resolve, reject) => {
-          reject(server.error(err.code, err.message, err.data));
-        });
-      }
-      return new Promise(resolve => {
-        const result = methodHandler("getRoot", params);
-        resolve(result);
-      });
-    });
-  }
+const server = jayson.server({
+  addTreeManually: params => checkAndCall("addTreeManually", "ctype1", params),
+  addTreeFromContract: params =>
+    checkAndCall("addTreeFromContract", "ctype2", params),
+  updateTreeManually: params =>
+    checkAndCall("updateTreeManually", "utype1", params),
+  extraUpdateTreeFromContract: params =>
+    checkAndCall("extraUpdateTreeFromContract", "utype2", params),
+  getProofByKey: async params => await require("./methods/getProofByKey")(params),
+  getProofByKeys: params => checkAndCall("getProofByKeys", "gp2", params),
+  getProofByKeyWithCondition: params =>
+    checkAndCall("getProofByKeyWithCondition", "gp3", params),
+  getProofByKeysWithCondition: params =>
+    checkAndCall("getProofByKeysWithCondition", "gp4", params),
+  getRoot: params => checkAndCall("getRoot", "gR", params)
 });
 
 server.http().listen(config.get("endpoint.options.port"));
diff --git a/proof-data-provider/yarn.lock b/proof-data-provider/yarn.lock
index edc9855..e5fbf58 100644
--- a/proof-data-provider/yarn.lock
+++ b/proof-data-provider/yarn.lock
@@ -2014,6 +2014,11 @@ jsonparse@^1.2.0:
   resolved "https://registry.yarnpkg.com/jsonparse/-/jsonparse-1.3.1.tgz#3f4dae4a91fac315f71062f8521cc239f1366280"
   integrity sha1-P02uSpH6wxX3EGL4UhzCOfE2YoA=
 
+jsonschema@^1.2.5:
+  version "1.2.5"
+  resolved "https://registry.yarnpkg.com/jsonschema/-/jsonschema-1.2.5.tgz#bab69d97fa28946aec0a56a9cc266d23fe80ae61"
+  integrity sha512-kVTF+08x25PQ0CjuVc0gRM9EUPb0Fe9Ln/utFOgcdxEIOHuU7ooBk/UPTd7t1M91pP35m0MU1T8M5P7vP1bRRw==
+
 jsprim@^1.2.2:
   version "1.4.1"
   resolved "https://registry.yarnpkg.com/jsprim/-/jsprim-1.4.1.tgz#313e66bc1e5cc06e438bc1b7499c2e5c56acb6a2"