diff --git a/e-dostavka.user.js b/e-dostavka.user.js
new file mode 100644
index 0000000..4852cca
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+++ b/e-dostavka.user.js
@@ -0,0 +1,90 @@
+// ==UserScript==
+// @name         [e-dostavka.by, gipermall.by] price comparison
+// @namespace    http://tampermonkey.net/
+// @version      2
+// @description  Show prices per kilo, compare between sites
+// @author       nomoreknights
+// @match        https://e-dostavka.by/*
+// @match        https://gipermall.by/*
+// @grant        unsafeWindow
+// @grant        GM.xmlHttpRequest
+// @require      https://cdnjs.cloudflare.com/ajax/libs/arrive/2.4.1/arrive.min.js
+// @require      https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js
+// @require      https://unpkg.com/ohm-js@0.14.0/dist/ohm.min.js
+// ==/UserScript==
+
+; (function ($) {
+    'use strict';
+    const price = (() => {
+        const priceGrammar = ohm.grammar(`Price { 
+                Price   = integer "р." integer "к." Price?
+                integer = digit+
+            }`)
+        const priceVal = priceGrammar.createSemantics().addOperation('val', {
+            Price: (rub, _1, kop, _2, _3) => rub.val() + kop.val() * 0.01,
+            integer: _ => parseInt(_.sourceString)
+        })
+        const weightGrammar = ohm.grammar(`Weight {
+                    Exp       = BS AnyWeight BS AnyWeight? BS
+                    AnyWeight = MulWeight | Weight
+                    Weight    = float (Unit1 | Unit10 | Unit1000) "."*
+                    MulWeight = float ("x" | "х" | "*") Weight
+                    float     = digit+ ("." digit+)? -- fl
+                    Unit1     = "г"  | "мл"
+                    Unit10    = "см"
+                    Unit1000  = "кг" | "л" | "м" | "шт"
+                    BS        = (~AnyWeight any)*
+                    }`)
+        const weightVal = weightGrammar.createSemantics().addOperation('val', {
+            Exp: (_1, weight, _2, _3, _4) => weight.val(),
+            Weight: (n, u, _1) => n.val() * u.val(),
+            MulWeight: (d, _, w) => d.val() * w.val(),
+            Unit1: _ => 0.001,
+            Unit10: _ => 0.01,
+            Unit1000: _ => 1,
+            float: _ => parseFloat(_.sourceString)
+        })
+        const interpret = (grammar, semantics, text) => {
+            const match = grammar.match(text)
+            if (match.failed()) console.log(`Failed to parse [${text}] with ${match.message}`)
+            return semantics(match).val()
+        }
+        return (price, weight) => interpret(priceGrammar, priceVal, price) / interpret(weightGrammar, weightVal, weight)
+    })()
+    const template = $("<a/>").css({
+        'background-color': '#fbba00',
+        'color': 'black', // default is #cb4f2b
+        'padding': '2px',
+        'border-radius': '5px',
+        'font-size': '14px',
+        'font-family': 'MyriadProCondencedBoldItalic',
+        'position': 'absolute',
+        'right': '5px'
+    }).attr('target', '_blank')
+    $(document).arrive(".products_card", { existing: true }, div => {
+        try {
+            const normalizedPrice = price(
+                $(div).find('div > form > div.prices__wrapper > div > div.prices_block > div > div.price').text(),
+                $(div).find('a.fancy_ajax').text()
+            )
+            const link = template.clone()
+            $(div).find('a.fa').replaceWith(link)
+            link.text(normalizedPrice.toFixed(2))
+            const url = (R.test(/e-dostavka/, location.host) ? R.identity : R.flip)(R.replace)('e-dostavka', 'gipermall', $(div).find('a.fancy_ajax').attr('href'))
+            GM.xmlHttpRequest({
+                method: 'GET', url, onload: page => {
+                    try {
+                        const html = $($.parseHTML(page.responseText))
+                        const competingPrice = price(
+                            html.find('div.services_wrap:nth-child(3) > div:nth-child(1) > div:nth-child(1) > div:nth-child(1)').text(),
+                            html.find('.template_1_columns > h1:nth-child(2)').text()
+                        )
+                        const diff = (1 - competingPrice / normalizedPrice) * 100
+                        link.text((_, text) => `${text} (${diff > 0 ? '>' : '<'}${Math.abs(diff).toFixed(0)}%)`)
+                            .prop('href', url)
+                    } catch (e) { console.log(`Failed to process page ${url}`, e) }
+                }
+            });
+        } catch (e) { console.log(`Failed to process product card with ${$(div).find('a.fancy_ajax').text()}`, e) }
+    });
+})(unsafeWindow.jQuery); // somehow, when @including jquery, infinite scroll stops working.
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