How to Integrate Lovable with Mint (now Credit Karma)

A Mint-replacement starts with bank connectivity. Plaid is the industry standard: it supports over 12,000 US financial institutions, provides automatic transaction categorization, and returns real-time balance data. The technical implementation involves three components: the Plaid Link frontend widget (which handles the bank login flow), an Edge Function that creates Link tokens and exchanges public tokens for access tokens, and a Supabase table that stores the access tokens and connection metadata. Go to dashboard.plaid.com and sign in to your developer account. Navigate to Team Settings → Keys and copy your Client ID and Sandbox Secret. You'll need these to store in Cloud Secrets. For a personal finance app, enable these Plaid products when creating your Link tokens: Transactions (for categorized transaction history), Balance (for real-time balance checks), and optionally Identity (to verify account ownership). In the Plaid Dashboard under the Products section, confirm your developer app has access to these products. The Plaid Sandbox lets you test with fake bank accounts without connecting real financial institutions. The test credentials are username: user_good, password: pass_good at 'First Platypus Bank'. This gives you a checking and savings account with pre-populated transaction history for testing all the dashboard features before going to production.

Plaid's Transactions product returns each transaction with automatic category labels from a hierarchical taxonomy. For example, a Starbucks purchase might have categories ['Food and Drink', 'Restaurants', 'Coffee Shop']. This built-in categorization is one of the most valuable features for a Mint replacement — it means you don't need to build your own categorization logic for the vast majority of transactions. Create an Edge Function that calls Plaid's /transactions/sync endpoint, which uses a cursor-based approach to return only new, modified, or deleted transactions since the last sync. On first sync, the cursor is empty and Plaid returns all available transaction history (up to 24 months on the Sandbox). Subsequent syncs return only changes. Map Plaid's transaction data to your Supabase transactions table. Store: transaction_id (Plaid's unique ID), user_id, account_id, date, name (merchant name), amount (positive for debits, negative for credits in Plaid's convention), primary_category (first element of Plaid's category array), detailed_category (second element), merchant_name, and pending (boolean for pending transactions). Set up an automatic daily sync using a Supabase scheduled trigger, and also provide a manual 'Sync Now' button in the app. Plaid also sends webhooks when new transactions are available — implementing a webhook receiver Edge Function gives you near-real-time transaction updates.

1// supabase/functions/plaid-transactions/index.ts
2import { serve } from "https://deno.land/std@0.168.0/http/server.ts";
3import { createClient } from "https://esm.sh/@supabase/supabase-js@2";
4
5const PLAID_ENV = Deno.env.get("PLAID_ENV") ?? "sandbox";
6const PLAID_BASE = `https://${PLAID_ENV}.plaid.com`;
7const CLIENT_ID = Deno.env.get("PLAID_CLIENT_ID") ?? "";
8const SECRET = Deno.env.get("PLAID_SECRET") ?? "";
9const corsHeaders = { "Access-Control-Allow-Origin": "*", "Access-Control-Allow-Methods": "POST, OPTIONS", "Access-Control-Allow-Headers": "Content-Type, Authorization" };
10
11serve(async (req) => {
12  if (req.method === "OPTIONS") return new Response(null, { headers: corsHeaders });
13  const supabase = createClient(Deno.env.get("SUPABASE_URL") ?? "", Deno.env.get("SUPABASE_SERVICE_ROLE_KEY") ?? "");
14
15  try {
16    const { user_id } = await req.json();
17    const { data: connections } = await supabase.from("plaid_connections").select("access_token, sync_cursor, item_id").eq("user_id", user_id);
18    if (!connections?.length) throw new Error("No connected accounts found");
19
20    let totalAdded = 0;
21    for (const conn of connections) {
22      let cursor = conn.sync_cursor ?? "";
23      let hasMore = true;
24      while (hasMore) {
25        const res = await fetch(`${PLAID_BASE}/transactions/sync`, {
26          method: "POST",
27          headers: { "Content-Type": "application/json" },
28          body: JSON.stringify({ client_id: CLIENT_ID, secret: SECRET, access_token: conn.access_token, cursor }),
29        });
30        const data = await res.json();
31        if (data.error_code) throw new Error(data.error_message);
32
33        if (data.added?.length > 0) {
34          await supabase.from("transactions").upsert(
35            data.added.map((t: any) => ({
36              transaction_id: t.transaction_id,
37              user_id,
38              account_id: t.account_id,
39              date: t.date,
40              name: t.name,
41              amount: t.amount,
42              primary_category: t.category?.[0] ?? "Other",
43              detailed_category: t.category?.[1] ?? "",
44              merchant_name: t.merchant_name ?? "",
45              pending: t.pending,
46            })),
47            { onConflict: "transaction_id" }
48          );
49          totalAdded += data.added.length;
50        }
51        if (data.removed?.length > 0) {
52          await supabase.from("transactions").delete().in("transaction_id", data.removed.map((r: any) => r.transaction_id));
53        }
54        cursor = data.next_cursor;
55        hasMore = data.has_more;
56        await supabase.from("plaid_connections").update({ sync_cursor: cursor }).eq("item_id", conn.item_id);
57      }
58    }
59    return new Response(JSON.stringify({ synced: totalAdded }), { headers: { ...corsHeaders, "Content-Type": "application/json" } });
60  } catch (err) {
61    return new Response(JSON.stringify({ error: err.message }), { status: 500, headers: { ...corsHeaders, "Content-Type": "application/json" } });
62  }
63});

With transactions flowing into Supabase, build the core Mint-like dashboard. The spending analysis view is the most valuable feature — it shows where money is going at a glance. Query the transactions table filtered by the current month and the current user. Group by primary_category and sum the amounts to get category totals. Display these as a donut or pie chart showing category proportions. Show the top 5 categories by spend in a ranked list below the chart. For the transaction list view, display all transactions sorted by date descending with: date, merchant name, category badge, and amount. Amounts should be colored red for debits (positive values in Plaid's convention) and green for credits (negative values — Plaid uses negative to indicate money received). Add filtering by category, date range, and search by merchant name. For budget vs. actual comparison, query the budgets table (from the budgets setup) and join with category totals from transactions to calculate remaining budget and percentage used. A progress bar component from shadcn/ui works well for displaying budget progress. For net worth, fetch all account balances from Plaid's balance endpoint via an Edge Function, sum checking and savings as assets, sum credit card and loan balances as liabilities, and show assets minus liabilities as net worth.

Budgets were Mint's most-used feature after account aggregation. Implement budget management with Supabase: a budgets table stores per-category monthly limits, and the dashboard compares actual spending to those limits. Create a Supabase table called budgets with columns: id, user_id, category (text, matching Plaid's primary_category values), monthly_limit (numeric), created_at. Apply RLS so users can only see and modify their own budgets. Build a budget setup page where users can see a list of spending categories (auto-populated from the distinct categories in their transactions table) and set a monthly limit for each. When no budget is set for a category, show the raw spending without a progress bar. For the month-over-month comparison chart, query the transactions table grouped by month and primary_category, returning the last 6 months of data per category. Display as a grouped bar chart showing each category's spending trend. This view — showing that restaurant spending has increased every month for 3 months — is the kind of insight that drives behavior change and made Mint genuinely useful. For users with Credit Karma migrated from Mint, point out in the onboarding that their historical Mint data is available as a CSV export from Credit Karma under Settings → Privacy, and provide a CSV import feature in your app to load historical transaction data.