diff --git a/monero_utils/MyMoneroCoreBridgeClass.js b/monero_utils/MyMoneroCoreBridgeClass.js
index cb9233c..4e2545b 100644
--- a/monero_utils/MyMoneroCoreBridgeClass.js
+++ b/monero_utils/MyMoneroCoreBridgeClass.js
@@ -34,26 +34,10 @@
 const JSBigInt = require("../cryptonote_utils/biginteger").BigInteger;
 const nettype_utils = require("../cryptonote_utils/nettype");
 //
-const MyMoneroBridgeClass_Base = require('./MyMoneroBridgeClass_Base')
+const MyMoneroCoreBridgeEssentialsClass = require('./MyMoneroCoreBridgeEssentialsClass')
 const MyMoneroBridge_utils = require('./MyMoneroBridge_utils')
 //
-function bridge_sanitized__spendable_out(raw__out)
-{
-	const sanitary__output = 
-	{
-		amount: raw__out.amount.toString(),
-		public_key: raw__out.public_key,
-		global_index: "" + raw__out.global_index,
-		index: "" + raw__out.index,
-		tx_pub_key: raw__out.tx_pub_key
-	};
-	if (raw__out.rct && typeof raw__out.rct !== 'undefined') {
-		sanitary__output.rct = raw__out.rct;
-	}
-	return sanitary__output;
-}
-//
-class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
+class MyMoneroCoreBridgeClass extends MyMoneroCoreBridgeEssentialsClass
 {
 	constructor(this_Module)
 	{
@@ -62,273 +46,10 @@ class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
 		this._register_async_cb_fns__send_funds();
 	}
 	//
-	//
-	is_subaddress(addr, nettype) {
-		const args =
-		{
-			address: addr,
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.is_subaddress(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg;
-		}
-		return MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.retVal);
-	}
-
-	is_integrated_address(addr, nettype) {
-		const args =
-		{
-			address: addr,
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.is_integrated_address(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg;
-		}
-		return MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.retVal);
-	}
-
-	new_payment_id() {
-		const args = {};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.new_payment_id(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg;
-		}
-		return ret.retVal;
-	}
-
-	new__int_addr_from_addr_and_short_pid(
-		address,
-		short_pid,
-		nettype
-	) {
-		if (!short_pid || short_pid.length != 16) {
-			throw "expected valid short_pid";
-		}
-		const args =
-		{
-			address: address,
-			short_pid: short_pid,
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.new_integrated_address(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg;
-		}
-		return ret.retVal;
-	}
-
-	decode_address(address, nettype)
-	{
-		const args =
-		{
-			address: address,
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.decode_address(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg;
-		}
-		return {
-			spend: ret.pub_spendKey_string,
-			view: ret.pub_viewKey_string,
-			intPaymentId: ret.paymentID_string, // may be undefined
-			isSubaddress: MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.isSubaddress)
-		}
-	}
-
-	newly_created_wallet(
-		locale_language_code,
-		nettype
-	) {
-		const args =
-		{
-			locale_language_code: locale_language_code, // NOTE: this function takes the locale, not the wordset name
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.newly_created_wallet(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg
-		}
-		return { // calling these out so as to provide a stable ret val interface
-			mnemonic_string: ret.mnemonic_string,
-			mnemonic_language: ret.mnemonic_language,
-			sec_seed_string: ret.sec_seed_string,
-			address_string: ret.address_string,
-			pub_viewKey_string: ret.pub_viewKey_string,
-			sec_viewKey_string: ret.sec_viewKey_string,
-			pub_spendKey_string: ret.pub_spendKey_string,
-			sec_spendKey_string: ret.sec_spendKey_string
-		};
-	}
-
-	are_equal_mnemonics(a, b) {
-		const args =
-		{
-			a: a,
-			b: b
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.are_equal_mnemonics(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg
-		}
-		return MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.retVal);
-	}
-
-	mnemonic_from_seed(
-		seed_string,
-		wordset_name
-	) {
-		const args =
-		{
-			seed_string: seed_string,
-			wordset_name: MyMoneroBridge_utils.api_safe_wordset_name(wordset_name)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.mnemonic_from_seed(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg // TODO: maybe return this somehow
-		}
-		return ret.retVal;
-	}
-
-	seed_and_keys_from_mnemonic(
-		mnemonic_string,
-		nettype
-	) {
-		const args =
-		{
-			mnemonic_string: mnemonic_string,
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.seed_and_keys_from_mnemonic(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg
-		}
-		return { // calling these out so as to provide a stable ret val interface
-			sec_seed_string: ret.sec_seed_string,
-			mnemonic_language: ret.mnemonic_language,
-			address_string: ret.address_string,
-			pub_viewKey_string: ret.pub_viewKey_string,
-			sec_viewKey_string: ret.sec_viewKey_string,
-			pub_spendKey_string: ret.pub_spendKey_string,
-			sec_spendKey_string: ret.sec_spendKey_string
-		};
-	}
-
-	validate_components_for_login(
-		address_string,
-		sec_viewKey_string,
-		sec_spendKey_string,
-		seed_string,
-		nettype
-	) {
-		const args =
-		{
-			address_string: address_string,
-			sec_viewKey_string: sec_viewKey_string,
-			sec_spendKey_string: sec_spendKey_string,
-			seed_string: seed_string,
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.validate_components_for_login(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg
-		}
-		return { // calling these out so as to provide a stable ret val interface
-			isValid: MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.isValid),
-			isInViewOnlyMode: MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.isInViewOnlyMode),
-			pub_viewKey_string: ret.pub_viewKey_string,
-			pub_spendKey_string: ret.pub_spendKey_string
-		};
-	}
-
-	address_and_keys_from_seed(
-		seed_string,
-		nettype
-	) {
-		const args =
-		{
-			seed_string: seed_string,
-			nettype_string: nettype_utils.nettype_to_API_string(nettype)
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.address_and_keys_from_seed(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg
-		}
-		return { // calling these out so as to provide a stable ret val interface
-			address_string: ret.address_string,
-			pub_viewKey_string: ret.pub_viewKey_string,
-			sec_viewKey_string: ret.sec_viewKey_string,
-			pub_spendKey_string: ret.pub_spendKey_string,
-			sec_spendKey_string: ret.sec_spendKey_string
-		};
-	}
-
-	generate_key_image(
-		tx_pub,
-		view_sec,
-		spend_pub,
-		spend_sec,
-		output_index
-	) {
-		if (tx_pub.length !== 64) {
-			throw "Invalid tx_pub length";
-		}
-		if (view_sec.length !== 64) {
-			throw "Invalid view_sec length";
-		}
-		if (spend_pub.length !== 64) {
-			throw "Invalid spend_pub length";
-		}
-		if (spend_sec.length !== 64) {
-			throw "Invalid spend_sec length";
-		}
-		if (typeof output_index === 'undefined' || output_index === "" || output_index === null) {
-			throw "Missing output_index";
-		}
-		const args =
-		{
-			sec_viewKey_string: view_sec,
-			sec_spendKey_string: spend_sec,
-			pub_spendKey_string: spend_pub,
-			tx_pub_key: tx_pub,
-			out_index: "" + output_index
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.generate_key_image(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg;
-		}
-		return ret.retVal;
-	}
-
+	// 
 	generate_key_derivation(
 		pub,
-		sec,
+		sec
 	) {
 		const args =
 		{
@@ -407,7 +128,7 @@ class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
 		const ecdhInfo = []; // should obvs be plural but just keeping exact names in-tact
 		for (var j = 0 ; j < rv.outPk.length ; j++) {
 			var this_ecdhInfo = rv.ecdhInfo[j];
-  			ecdhInfo.push({
+			ecdhInfo.push({
 				mask: this_ecdhInfo.mask,
 				amount: this_ecdhInfo.amount
 			})
@@ -424,7 +145,7 @@ class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
 			if (this_outPk_mask == null) {
 				throw "Couldn't locate outPk mask value";
 			}
-  			outPk.push({
+			outPk.push({
 				mask: this_outPk_mask
 			})
 		}
@@ -454,7 +175,7 @@ class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
 		const ecdhInfo = []; // should obvs be plural but just keeping exact names in-tact
 		for (var j = 0 ; j < rv.outPk.length ; j++) {
 			var this_ecdhInfo = rv.ecdhInfo[j];
-  			ecdhInfo.push({
+			ecdhInfo.push({
 				mask: this_ecdhInfo.mask,
 				amount: this_ecdhInfo.amount
 			})
@@ -471,7 +192,7 @@ class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
 			if (this_outPk_mask == null) {
 				return { err_msg: "Couldn't locate outPk mask value" }
 			}
-  			outPk.push({
+			outPk.push({
 				mask: this_outPk_mask
 			})
 		}
@@ -496,23 +217,6 @@ class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
 			mask: ret.mask,
 		};
 	}
-	estimated_tx_network_fee(fee_per_kb__string, priority, optl__fee_per_b_string) // this is until we switch the server over to fee per b
-	{ // TODO update this API to take object rather than arg list
-		const args =
-		{
-			fee_per_b: typeof optl__fee_per_b_string !== undefined && optl__fee_per_b_string != null 
-				? optl__fee_per_b_string 
-				: (new JSBigInt(fee_per_kb__string)).divide(1024).toString()/*kib -> b*/, 
-			priority: "" + priority,
-		};
-		const args_str = JSON.stringify(args);
-		const ret_string = this.Module.estimated_tx_network_fee(args_str);
-		const ret = JSON.parse(ret_string);
-		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
-			throw ret.err_msg; // TODO: maybe return this somehow
-		}
-		return ret.retVal; // this is a string - pass it to new JSBigInt(…)
-	}
 	estimate_rct_tx_size(n_inputs, mixin, n_outputs, extra_size, bulletproof)
 	{
 		const args =
@@ -557,19 +261,6 @@ class MyMoneroCoreBridgeClass extends MyMoneroBridgeClass_Base
 	{
 		return `fromCpp__send_funds__success-${task_id}`
 	}
-	__new_cb_args_with(task_id, err_msg, res)
-	{
-		const args = 
-		{
-			task_id: task_id
-		};
-		if (typeof err_msg !== 'undefined' && err_msg) {
-			args.err_msg = err_msg; // errors must be sent back so that C++ can free heap vals container
-		} else {
-			args.res = res;
-		}
-		return args;
-	}
 	_register_async_cb_fns__send_funds()
 	{
 		const self = this
diff --git a/monero_utils/MyMoneroCoreBridgeEssentialsClass.js b/monero_utils/MyMoneroCoreBridgeEssentialsClass.js
new file mode 100644
index 0000000..daf44be
--- /dev/null
+++ b/monero_utils/MyMoneroCoreBridgeEssentialsClass.js
@@ -0,0 +1,329 @@
+// Copyright (c) 2014-2019, MyMonero.com
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//	conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//	of conditions and the following disclaimer in the documentation and/or other
+//	materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//	used to endorse or promote products derived from this software without specific
+//	prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Original Author: Lucas Jones
+// Modified to remove jQuery dep and support modular inclusion of deps by Paul Shapiro (2016)
+// Modified to add RingCT support by luigi1111 (2017)
+//
+// v--- These should maybe be injected into a context and supplied to currencyConfig for future platforms
+const JSBigInt = require("../cryptonote_utils/biginteger").BigInteger;
+const nettype_utils = require("../cryptonote_utils/nettype");
+//
+const MyMoneroBridgeClass_Base = require('./MyMoneroBridgeClass_Base')
+const MyMoneroBridge_utils = require('./MyMoneroBridge_utils')
+//
+class MyMoneroCoreBridgeEssentialsClass extends MyMoneroBridgeClass_Base
+{
+	constructor(this_Module)
+	{
+		super(this_Module);
+	}
+	//
+	//
+	is_subaddress(addr, nettype) {
+		const args =
+		{
+			address: addr,
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.is_subaddress(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg;
+		}
+		return MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.retVal);
+	}
+
+	is_integrated_address(addr, nettype) {
+		const args =
+		{
+			address: addr,
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.is_integrated_address(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg;
+		}
+		return MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.retVal);
+	}
+
+	new_payment_id() {
+		const args = {};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.new_payment_id(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg;
+		}
+		return ret.retVal;
+	}
+
+	new__int_addr_from_addr_and_short_pid(
+		address,
+		short_pid,
+		nettype
+	) {
+		if (!short_pid || short_pid.length != 16) {
+			throw "expected valid short_pid";
+		}
+		const args =
+		{
+			address: address,
+			short_pid: short_pid,
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.new_integrated_address(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg;
+		}
+		return ret.retVal;
+	}
+
+	decode_address(address, nettype)
+	{
+		const args =
+		{
+			address: address,
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.decode_address(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg;
+		}
+		return {
+			spend: ret.pub_spendKey_string,
+			view: ret.pub_viewKey_string,
+			intPaymentId: ret.paymentID_string, // may be undefined
+			isSubaddress: MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.isSubaddress)
+		}
+	}
+
+	newly_created_wallet(
+		locale_language_code,
+		nettype
+	) {
+		const args =
+		{
+			locale_language_code: locale_language_code, // NOTE: this function takes the locale, not the wordset name
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.newly_created_wallet(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg
+		}
+		return { // calling these out so as to provide a stable ret val interface
+			mnemonic_string: ret.mnemonic_string,
+			mnemonic_language: ret.mnemonic_language,
+			sec_seed_string: ret.sec_seed_string,
+			address_string: ret.address_string,
+			pub_viewKey_string: ret.pub_viewKey_string,
+			sec_viewKey_string: ret.sec_viewKey_string,
+			pub_spendKey_string: ret.pub_spendKey_string,
+			sec_spendKey_string: ret.sec_spendKey_string
+		};
+	}
+
+	are_equal_mnemonics(a, b) {
+		const args =
+		{
+			a: a,
+			b: b
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.are_equal_mnemonics(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg
+		}
+		return MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.retVal);
+	}
+
+	mnemonic_from_seed(
+		seed_string,
+		wordset_name
+	) {
+		const args =
+		{
+			seed_string: seed_string,
+			wordset_name: MyMoneroBridge_utils.api_safe_wordset_name(wordset_name)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.mnemonic_from_seed(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg // TODO: maybe return this somehow
+		}
+		return ret.retVal;
+	}
+
+	seed_and_keys_from_mnemonic(
+		mnemonic_string,
+		nettype
+	) {
+		const args =
+		{
+			mnemonic_string: mnemonic_string,
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.seed_and_keys_from_mnemonic(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg
+		}
+		return { // calling these out so as to provide a stable ret val interface
+			sec_seed_string: ret.sec_seed_string,
+			mnemonic_language: ret.mnemonic_language,
+			address_string: ret.address_string,
+			pub_viewKey_string: ret.pub_viewKey_string,
+			sec_viewKey_string: ret.sec_viewKey_string,
+			pub_spendKey_string: ret.pub_spendKey_string,
+			sec_spendKey_string: ret.sec_spendKey_string
+		};
+	}
+
+	validate_components_for_login(
+		address_string,
+		sec_viewKey_string,
+		sec_spendKey_string,
+		seed_string,
+		nettype
+	) {
+		const args =
+		{
+			address_string: address_string,
+			sec_viewKey_string: sec_viewKey_string,
+			sec_spendKey_string: sec_spendKey_string,
+			seed_string: seed_string,
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.validate_components_for_login(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg
+		}
+		return { // calling these out so as to provide a stable ret val interface
+			isValid: MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.isValid),
+			isInViewOnlyMode: MyMoneroBridge_utils.ret_val_boolstring_to_bool(ret.isInViewOnlyMode),
+			pub_viewKey_string: ret.pub_viewKey_string,
+			pub_spendKey_string: ret.pub_spendKey_string
+		};
+	}
+
+	address_and_keys_from_seed(
+		seed_string,
+		nettype
+	) {
+		const args =
+		{
+			seed_string: seed_string,
+			nettype_string: nettype_utils.nettype_to_API_string(nettype)
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.address_and_keys_from_seed(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg
+		}
+		return { // calling these out so as to provide a stable ret val interface
+			address_string: ret.address_string,
+			pub_viewKey_string: ret.pub_viewKey_string,
+			sec_viewKey_string: ret.sec_viewKey_string,
+			pub_spendKey_string: ret.pub_spendKey_string,
+			sec_spendKey_string: ret.sec_spendKey_string
+		};
+	}
+
+	generate_key_image(
+		tx_pub,
+		view_sec,
+		spend_pub,
+		spend_sec,
+		output_index
+	) {
+		if (tx_pub.length !== 64) {
+			throw "Invalid tx_pub length";
+		}
+		if (view_sec.length !== 64) {
+			throw "Invalid view_sec length";
+		}
+		if (spend_pub.length !== 64) {
+			throw "Invalid spend_pub length";
+		}
+		if (spend_sec.length !== 64) {
+			throw "Invalid spend_sec length";
+		}
+		if (typeof output_index === 'undefined' || output_index === "" || output_index === null) {
+			throw "Missing output_index";
+		}
+		const args =
+		{
+			sec_viewKey_string: view_sec,
+			sec_spendKey_string: spend_sec,
+			pub_spendKey_string: spend_pub,
+			tx_pub_key: tx_pub,
+			out_index: "" + output_index
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.generate_key_image(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg;
+		}
+		return ret.retVal;
+	}
+	estimated_tx_network_fee(fee_per_kb__string, priority, optl__fee_per_b_string) // this is until we switch the server over to fee per b
+	{ // TODO update this API to take object rather than arg list
+		const args =
+		{
+			fee_per_b: typeof optl__fee_per_b_string !== undefined && optl__fee_per_b_string != null 
+				? optl__fee_per_b_string 
+				: (new JSBigInt(fee_per_kb__string)).divide(1024).toString()/*kib -> b*/, 
+			priority: "" + priority,
+		};
+		const args_str = JSON.stringify(args);
+		const ret_string = this.Module.estimated_tx_network_fee(args_str);
+		const ret = JSON.parse(ret_string);
+		if (typeof ret.err_msg !== 'undefined' && ret.err_msg) {
+			throw ret.err_msg; // TODO: maybe return this somehow
+		}
+		return ret.retVal; // this is a string - pass it to new JSBigInt(…)
+	}
+}
+//
+module.exports = MyMoneroCoreBridgeEssentialsClass
\ No newline at end of file