Why Vernacular Is Not a Feature, It's a Foundation

Before we ran hoardings across the Hindi belt, we ran pre-tests.

Not on the hoardings — you can't A/B test a billboard. But on Meta ads and push notifications, we tested the same creative in English against localized versions in Hindi, Bengali, and Marathi.

Same offer. Same visual structure. Same product. Different language.

The results weren't close.

In certain regions, localized communication drove ~65% higher CTRs than the generic English version.

65% is not a rounding error. It's not a nice-to-have. It's the difference between a campaign that works and one that doesn't.

And yet, most companies treat vernacular as a feature — something you add later, once the core product is working, as part of a "localization sprint." A checkbox on the roadmap.

That framing is wrong. And it costs companies more than they realize.

Language Is a Trust Signal Before It's a Comprehension Aid

Here's the thing about the tier 2–3 India user that most growth teams miss: they can often understand English. Especially the younger cohort — anyone who's gone through an English-medium school system has functional English comprehension.

But understanding something and feeling spoken to are different things.

When a student in Dhanbad preparing for SSC CGL sees a push notification in Hindi, something specific happens that doesn't happen with an English notification: they recognize themselves in it.

The message feels like it was written for them, not translated for them.

That recognition is a trust signal. It precedes comprehension. It happens before the user has even processed what the message says.

Language, in this context, is not primarily about accessibility. It's about belonging.

It signals:

"We know who you are, and we built this for you."

For a user who has spent years consuming products designed for someone else — English-first, urban-first, credit-card-first products — that signal is unusually powerful.

What We Actually Tested

The pre-test methodology was straightforward:

Variants tested:

• English (control)
• Hindi
• Bengali (West Bengal and northeastern markets)
• Marathi (Maharashtra outside Mumbai)

Conditions: Identical targeting parameters, identical budget allocation, simultaneous runs on Meta and push notifications.

The pattern was consistent:

Vernacular outperformed English significantly across regions. The gap was larger in lower-tier markets than in higher-tier ones.

This makes intuitive sense. A user in Bengaluru or Pune has spent years in an English-language digital environment. The further you go from the metro, the more language matters as a trust proxy.

Push notifications outperformed Meta ads in vernacular uplift — probably because push is more personal. A message on your phone screen, in your language, at the right moment, feels different from an ad in a feed.

What This Means for Product, Not Just Marketing

The mistake most companies make: treating vernacular as a marketing problem.

Translate the push notifications. Localize the ad copy. Job done.

But if language is a trust signal, it can't stop at the communication layer. The moment a user clicks through from a Hindi push notification to an English product experience, the trust you just built evaporates.

At Testbook, this influenced how we thought about the entire funnel:

• ✅ Acquisition communications
• ✅ Onboarding flows
• ✅ In-app messaging
• ✅ Test content
• ✅ Community channels — WhatsApp groups in Hindi for Hindi-belt markets

The WhatsApp communities felt like they belonged to the users, not to us — because the conversations happening in them were in Hindi. That's not a small thing.

The Broader Principle

ChatGPT has 100 million weekly users in India. The product is primarily English. The next 100 million users — the ones who will actually move the monetization needle — are in tier 2 and tier 3 markets where Hindi, Bengali, Tamil, Telugu, and Marathi are the primary languages of daily life.

Offering Hindi as a language option is a feature.

Building a product that feels genuinely native to a Hindi-speaking user — where the default experience, the onboarding, the error messages, the community, the support — is all in Hindi — that's a foundation.

The difference is not cosmetic. It's the difference between a product that serves this user and a product that tolerates them.

A Practical Starting Point

If you haven't done language testing yet, start here:

Step 1: Take your best-performing campaign creative 

Step 2: Produce versions in your top 2 regional languages — same offer, same structure, same targeting 

Step 3: Run simultaneously, measure CTR, click-to-conversion, and CPA separately 

Step 4: Read the gap

Whatever the result, you'll learn something useful:

• If vernacular outperforms significantly (likely) → clear mandate to invest
• If it doesn't → you have data that tells you where in the funnel the language gap actually sits

Either way, you'll have stopped treating vernacular as an assumption and started treating it as a variable. That shift in mindset is where a good localization strategy begins.

Dhairya Mehta is Director of Growth and Marketing at Testbook, where he owns the P&L of India's largest exam-prep subscription. He writes about growth, India's developing market, and building things.

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