Express.js Schema Diff — Compare Node.js Database Schemas Online

Express.js Schema Diff.
Compare Node.js migrations.
Zero setup.

Paste two CREATE TABLE dumps from your Express app — whether from Sequelize migrations, Prisma schema SQL, TypeORM sync, or raw SQL. Spot every table, column, index, and constraint change instantly. Get ready-to-run ALTER TABLE scripts for MySQL or PostgreSQL — all in your browser.

No account required. No data leaves your device.

Built for Express & Node.js workflows

SchemaLens understands Node.js-specific patterns that generic diff tools miss.

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Sequelize Migration Review

Compare up and down migration outputs from sequelize-cli db:migrate. Verify that model syncs and query interface changes produce the schema you expected.

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Prisma Schema Sync

Diff the SQL emitted by prisma migrate dev or prisma db pull. Catch unexpected column drops, type remappings, and index changes before they hit production.

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TypeORM Entity Changes

Detects changes when synchronize: true generates new DDL. Warns about @Column type changes, @JoinColumn shifts, and @Index modifications.

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Foreign Key & Relations

Validates belongsTo, hasMany, and belongsToMany foreign keys in Sequelize. Detects missing or changed constraints that could break eager loading and associations.

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JSON Column Diff

Compares JSON and JSONB column declarations — critical for Express apps using PostgreSQL JSON schemas or MySQL JSON fields for flexible document storage.

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Privacy First

Your schema never leaves the browser. Compare production Express schemas safely without uploading sensitive table structures to a third-party server.

How it works with Express.js

Dump your schemas

Run npx sequelize-cli db:migrate:status or export from Prisma/TypeORM. Capture SQL from both environments (local vs staging, or staging vs production).

Paste into SchemaLens

Copy the SQL into the two editor panes. Dialect auto-detects MySQL or PostgreSQL based on your DATABASE_URL or config/database.js.

Review the diff

See added tables, dropped columns, type changes, and constraint modifications highlighted in color. Check for breaking changes before deploying your npm run deploy.

Copy the migration

Export ALTER TABLE scripts, save as Markdown for PR descriptions, or generate rollback SQL. Run in staging, then production.

Express.js migration examples

SchemaLens generates production-ready ALTER TABLE scripts for every change it detects.

Add a new column

ALTER TABLE `users`
  ADD COLUMN `email_verified` BOOLEAN DEFAULT FALSE;

Change JSON schema

ALTER TABLE `events`
  ALTER COLUMN `payload` TYPE JSONB;

Add a foreign key

ALTER TABLE `orders`
  ADD CONSTRAINT `orders_user_id_fkey`
  FOREIGN KEY (`user_id`) REFERENCES `users`(`id`)
  ON DELETE CASCADE;

Add an index for queries

CREATE INDEX `idx_orders_status`
  ON `orders`(`status`, `created_at`);

Related guides

Node.js