SMS keywords for ecommerce: how to choose, launch and stay compliant
SMS keywords are words a customer texts to your number to trigger an action. Subscribe keywords, such as JOIN or a campaign word, opt people into a list. Compliance keywords, such as STOP and HELP, remove consent or return required information. Every program must honor the compliance set; the subscribe keywords are where list growth happens.
The two kinds of keywords
Most confusion about SMS keywords comes from treating the two kinds as one. Compliance keywords exist because the law and the carriers require them, and you do not choose them. Subscribe keywords are marketing: you pick them, print them and measure them.
| Type | Examples | What it does | Can you edit it? |
|---|---|---|---|
| Compliance | STOP, HELP, START, UNSTOP | Removes or restores consent, or returns contact and program details | No. In Klaviyo, for example, the opt-out and resubscribe replies cannot be edited in the US and Canada |
| Subscribe | JOIN, VIP, a campaign word | Adds the sender to a list and starts the confirmation flow | Yes, you choose the word, list and reply |
The opt-out words you must honor
The FCC’s consent revocation rules took effect on 11 April 2025. A reply of stop, quit, end, revoke, opt out, cancel or unsubscribe to a text message counts as a valid revocation, and it must be honored within a reasonable time not to exceed ten business days. A separate rule lets you send one confirmation text within five minutes of the request, with no marketing in it. The FCC’s broader revoke-all provision, which would make one opt-out cover unrelated message types, has been delayed to 31 January 2027.
CTIA’s Messaging Principles and Best Practices, the May 2023 edition carriers work from, adds the practical layer: standardized STOP wording in opt-out instructions, one final opt-out confirmation, and nothing after it. Plain-language opt-outs such as “please stop texting me” should be honored too. Treat any clear request as a STOP, whatever the exact word.
How to choose a subscribe keyword
A good keyword is short, spelled one way, and tied to the moment someone sees it. Klaviyo’s rules are a sensible baseline for any platform: letters and numbers only, 3 to 20 characters, not case-sensitive, and never a word that already exists as a subscribe or compliance keyword. Klaviyo also blocks common words such as “the” or “here” so a normal reply does not subscribe someone by accident, and blocks words related to sex, hate, alcohol, firearms or tobacco.
- Use one keyword per placement, so you can see which channel produced the sign-up: one for packaging inserts, one for in-store signs, one for paid social.
- Match the keyword to the offer people will get: GLOW for a skincare launch, DROP for a release list.
- Avoid words people misspell or autocorrect changes.
- Keep the confirmation reply complete. CTIA expects it to name the program, give HELP or contact details, explain how to opt out, state that messages recur and how often, and disclose any fees.
Double opt-in, or single?
Klaviyo defaults keyword sign-ups to double opt-in, where the subscriber confirms before being added, and recommends single opt-in only for tap-to-text links that open a prefilled message. We follow the same rule. A keyword printed on a poster or packaging gets double opt-in, because anyone can text it. A tap-to-text button inside your own email or site, where the sender clearly meant to subscribe, can use single opt-in.
A complete confirmation reply covers every CTIA element in two short lines. For example: “Glow Club: reply Y to get launch alerts and offers from Brand, up to 6 texts a month. Msg and data rates may apply. Reply HELP for help, STOP to cancel.” Then deliver what the keyword promised in the first message after confirmation, while the subscriber is still holding the phone.
How to measure a keyword
Give every keyword its own list or source tag, then read four numbers each month. Sign-ups per keyword tells you which placement works. Confirmation rate, the share who complete double opt-in, tells you whether the offer and reply are clear. First-order rate within 30 days tells you whether the people joining buy. Unsubscribe rate in the first 30 days tells you whether the program delivered what the keyword promised. Retire keywords that sign people up who never buy, and reuse the ones that do on the next campaign.
Where keywords actually grow a list
Keywords grow lists where a form cannot reach: packaging, receipts, events, retail shelves, influencer videos and podcasts. On your own website, a sign-up form or tap-to-text unit converts better because it captures the email and phone together. Our SMS list growth guide covers the full mix.
List growth compounds when the welcome texts land well. For Darc Sport, the SMS subscriber base reached 21,000 within a month of launching on Attentive and nearly doubled to 41,000 within two months. Keywords were one entry point among several; the consistent piece was a clear offer and a confirmation flow that delivered it immediately.
Our SMS marketing agency sets up keywords, confirmation flows and source tracking on Attentive, Klaviyo or Postscript, and our SMS marketing best practices cover what to send once people join.
