Sendblue and LoopMessage are both long-standing vendors with public documentation and free sandboxes, which already puts them ahead of much of the category. They differ in who they are built for, and that shows up first in the pricing.
The money
| Sendblue | LoopMessage | |
|---|---|---|
| Sandbox | Free | Free, capped at 5 contacts |
| Cheapest paid entry | $100/month per dedicated line | $20/month shared sender |
| Dedicated line | $100/month | From $59.99/month (Light) |
| Higher tier | Enterprise, custom | From $99.99/month (Regular) |
| Billing model | Per line | Per plan, with volume tiers |
LoopMessage's shared sender at $20 is the lowest real entry point in the category and the single strongest reason to choose it. The number is shared, so it is right for transactional sends and wrong if you want the customer to save you as a contact.
Where the crossover sits
At genuinely low volume — a few dozen messages a month — LoopMessage is dramatically cheaper. Once you need a dedicated number, the gap narrows to a difference that should not drive the decision. Work out your monthly volume first; it settles this comparison faster than any feature table. The per-line arithmetic is here.
The developer experience
Both publish documentation you can read without an account, which is the bar. Sendblue's request shapes are documented in enough detail to write a client from the page. LoopMessage's reference is public and their sandbox contact cap of five is worth knowing before you plan a test — it is enough to validate the integration and not enough to trial a campaign.
Neither requires an SDK. A client for either is about forty lines of Node or Python.
Fallback
Sendblue's automatic SMS and RCS fallback is the feature most worth paying for if a meaningful share of your list is on Android — one API call, correct channel, no routing logic in your code. Confirm LoopMessage's current fallback behaviour against their documentation rather than a comparison table, including this one; it is the kind of feature that changes without announcement.
Choosing
| If | Then |
|---|---|
| You send under ~100 messages a month | LoopMessage |
| A dedicated number matters to you | Either — compare on fallback and docs |
| A large share of your list is on Android | Sendblue, for the fallback |
| You are testing the channel at all | LoopMessage's $20 tier is the cheapest real test |
| You need a shared inbox for non-developers | Neither — Miss Blue |
The one-hour test
- Open both sandboxes. Neither asks for a card.
- Send the same message from each to the same iPhone.
- Compare the delivery events you get back, and how quickly.
- Reply from the phone and compare the inbound webhook payloads.
- Note how often you had to leave the docs to work something out.
- Then price both at your actual monthly volume.
Full pricing across the category is on the pricing page, and the wider alternatives are here.