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Jon

Posted on • Originally published at schemacheck.co

How to Validate CSV and JSON Files Online with SchemaCheck

#csv #json #data #api

🚨 The Pain: Broken Imports and Bad Data

You upload a CSV to your app — maybe Shopify, Xero, or your internal database — and boom:

“Import failed. Invalid format.”

Sound familiar?
CSV imports fail for dozens of reasons:

  • Missing or renamed headers
  • Wrong data types (e.g., “ten” instead of 10)
  • Empty required fields
  • Incorrect date formats (MM/DD/YYYY instead of YYYY-MM-DD)
  • Extra columns or stray commas

It’s frustrating, time-consuming, and completely preventable.

That’s where schema validation comes in.

✅ What Is CSV Schema Validation?

Schema validation means you define the structure your CSV must follow, and the tool automatically checks whether your file matches it.

A simple schema describes:

  • Expected column names
  • Data types (string, number, date, email, etc.)
  • Required or optional fields
  • Value constraints (length, min/max, enum lists)

If the file doesn’t match, you get a clear, row-by-row report of what’s wrong — before you upload it anywhere.

🧩 Example: Validating a Customer CSV

Let’s say your app expects this format:

id email amount date
1 user@example.com 49.99 2025-10-12

You can define this schema:

{
  "type": "csv_schema",
  "columns": [
    { "name": "id", "type": "integer", "required": true },
    { "name": "email", "type": "email", "required": true },
    { "name": "amount", "type": "number", "minimum": 0 },
    { "name": "date", "type": "date", "format": "YYYY-MM-DD" }
  ]
}
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If a file contains a typo like example[at]domain.com or a missing header, the validator flags it instantly.

⚙️ How SchemaCheck Simplifies This

Instead of manually running scripts or writing one-off validation logic, SchemaCheck lets you:

  • 🧱 Define reusable CSV schemas visually or via JSON
  • ⚡ Validate files online (no setup, no code)
  • 📊 Get detailed error reports showing exact rows and reasons
  • 🔒 Validate securely — files are processed in-memory and deleted after validation

Try it instantly on the CSV Validator
— no signup, no credit card required.

🧠 Why Validate Before Importing?

A few reasons developers and data teams do this:

  1. Avoid downtime from failed imports
  3. Protect your database from malformed data
  5. Save engineering time debugging broken ETL pipelines
  7. Catch human errors early (especially from spreadsheets)
  9. Standardize file formats across teams

The earlier you catch data errors, the cheaper they are to fix.

💡 Pro Tip: Automate CSV Checks in Your Workflow

If you’re validating CSVs regularly — e.g., before pushing data into Postgres, Snowflake, or S3 — you can use the SchemaCheck Validation API
to automate it.

Example:

curl -X POST "https://schemacheck.co/api/v1/validate?schema_id=YOUR_SCHEMA_ID" \
  -H "Authorization: Bearer sc_YOUR_API_KEY" \
  -F "file=@data.[csv/json]"
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The API returns a JSON report showing any invalid rows — perfect for CI/CD or ETL pipelines.

🚀 Start Validating CSVs Today

Don’t waste another hour debugging CSV import errors.
SchemaCheck helps you catch data issues before they reach production.

👉 Validate Your CSV Files Free

(No credit card required — 1MB limit on free tier)

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