The best tools for adding dynamic images to emails
Adding dynamic images to emails sounds like a technical project. For most teams it isn't anymore. The hard part now is choosing the right approach, because "dynamic image" means different things depending on who's selling it.
This guide sorts out the options, explains what each is good for, and makes the case for the approach that fits most email teams: an email-first platform like Alterable.
Two very different meanings of "dynamic image"
Some tools pick an image. Others make one.
Picking means choosing between images you've already designed: winter coats for Chicago, raincoats for Seattle, a generic image for everyone else. Many email platforms can do this with conditional blocks at send time. It's useful, but every variation is something you had to design, and the choice is locked once the email goes out.
Making means generating the image for each subscriber when they open the email. The name, the balance, the countdown, the nearest store, the current price: all drawn at that moment. Nobody designed a separate version for each subscriber. That's what open-time image tools do, and it's what most people actually picture when they say "dynamic images."
Option 1: Your ESP's built-in features
Start by checking what your platform already does. Conditional blocks, segment-based content, and product recommendation blocks can take you a long way for send-time personalization.
Where they stop: they can't put a unique value into an image, they can't update after sending, and each platform does it differently, so what you build in one ESP doesn't carry over to another.
Option 2: Build it yourself
A developer can build an image server that takes parameters and returns a generated image. It's a fun project, and it's harder than it looks. You'll need fast rendering at open-time volume, caching that doesn't serve stale images, fallbacks, font handling, retina sizes, email client quirks, and image proxies from Gmail and Apple Mail that change how requests arrive. Then someone has to maintain it.
For most marketing teams, that time is better spent on campaigns.
Option 3: An email-first open-time platform
These tools do the rendering for you and are designed around how email actually works. You build the image in a browser, paste one image tag into your ESP, and each subscriber sees their own version.
This is the right choice for most teams, and it's where Alterable fits.
Why Alterable is the best tool for adding dynamic images to emails
Set up in minutes, not sprints
Upload your artwork, add variables where personal values should go, set a default for each, and copy the embed. Alterable has step-by-step guides for Klaviyo, Mailchimp, HubSpot, and other major platforms, covering the exact merge tag syntax for each. There's no integration to maintain.
More than names
Alterable images can carry names, loyalty balances, coupon codes, expiry dates, and anything else in your subscriber data. Rules can switch the image by location, device, language, time of day, or weather. And anything you can expose through an API, like order status or stock levels, can render into an image that updates each time it's reopened.
Everything in one account
Dynamic images sit alongside countdown timers, dynamic product blocks, store maps, surveys, and scratch cards. They all use the same builder and the same embed approach, and they're all included on every plan.
Free to start
The free plan includes dynamic images with 10,000 impressions a month, no watermark, and no credit card. Pro is $49 a month for 500,000 impressions, and adds A/B testing, unlimited rule-based versions, an API, a Zapier integration, and an MCP server.
Safe for deliverability
Alterable content is delivered as standard images, the same as any image your ESP already sends. There's no JavaScript in the email, and nothing changes about your sending domain or authentication.
How to add your first dynamic image
- Pick one important email where personalization would matter, like your welcome email or a loyalty update.
- In Alterable, create a dynamic image from your existing artwork and add the variables you want.
- Set fallbacks for subscribers with missing data.
- Copy the embed and swap in your ESP's merge tags, following the guide for your platform.
- Paste it into an HTML or code block, not a standard image block, so merge tags can go inside the image URL.
- Preview with real contacts, including ones missing data, then send.
Designing dynamic images that look intentional
Leave room for variable text. Names range from "Al" to "Anastasia-Josephine," and your layout should handle both. Choose fonts that support accents and special characters. Keep the most important message and the call to action outside the image as live text and a button, so the email still works with images off. And write alt text that makes sense without the personalization, like "Your rewards summary."
What to expect
A personalized image won't rescue a weak offer. What it does is make a relevant offer feel personal, and that shows up in clicks. The only numbers that matter are yours, so run a simple split: your usual image against a personalized one, same email, same audience.
If dynamic images have been sitting on your "someday" list because they sounded complicated, this is a good week to cross one off.