ComparisoniMessage API5 min read
iMessage API pricing compared
iMessage API pricing explained: start free with Flow, support 300 people a month on a $25 shared line, and scale with a $100 a month dedicated line.
The short answer
Flow is the best value for an iMessage agent: start free, support 300 people a month on a $25 shared line, or scale with a $100 a month dedicated line for 1,000 people a day (a new line starts at 250 a day and ramps to 1,000 over its first 14 days). There are no per-message fees, and one codebase runs across iMessage, WhatsApp, Telegram and MCP.
Building on the iMessage API? Build on iMessage with Flow: one agent for iMessage, WhatsApp and Telegram. New to it? Read the iMessage API guide.
What each company lists
Prices are from each company's public pages as of October 2026. Flow's come from its iMessage plans.
| Feature | flow.engineer | Sendblue | Twilio | Linq |
|---|---|---|---|---|
| Price to start | Free trial for 25 people; $25 shared line for 300 people a month and 200 a day; $100 a month dedicated line for 1,000 people a day (250 a day at first, ramping to 1,000 over its first 14 days); writing first with the $40 a month Outbound add-on on a dedicated line, where new conversations ramp from 2 a day to 40 a day over 21 days | $100 a month per dedicated line (AI Agent plan); outbound is custom1 | US SMS from $0.0083 per segment, plus carrier fees and 10DLC fees2 | Pro from $260 a month; Enterprise custom3 |
| Message limits | No per-message fees. Plans cap different people, not messages, per account and channel by UTC day and month, replies included: 25 free on the trial (no monthly reset), 300 a month and 200 a day on the $25 shared plan, 1,000 a day on a dedicated line after a 14-day ramp from 250. Writing first is paced | No per-message fees; 1,000 inbound contacts a day on the AI Agent plan1 | Priced per message | No per-message pricing stated3 |
| Your agent can write first | With the $40 a month Outbound add-on, on a dedicated line; new conversations ramp from 2 a day to 40 a day over 21 days. Otherwise customers text first | Enterprise plan only. The $100 AI Agent plan is inbound-first1 | Not applicable (SMS can be sent to anyone) | Not stated on the pricing page; the CLI shows creating a chat to a number4 |
| Free way to try it | Free trial on the shared line: 25 people, customers text first. Plus a $25 shared line for 300 people a month, a Telegram sandbox and simulated contacts | Sandbox: shared number, 10 verified contacts, inbound-first1 | Trial account (not for iMessage) | Hobby plan: $0, 20 contacts3 |
Last checked: October 2026. Prices and features change, so check each provider’s own pages before you rely on a detail. “Check with the provider” means we did not find it stated.
Flow pricing and worked examples
Flow’s iMessage plans are by line and by people. These are the plans and the Outbound add-on, from Flow on iMessage:
| Plan | Price | People per channel | Writes first? |
|---|---|---|---|
| Free (shared line) | $0 | 25 (a trial, no monthly reset) | No |
| Shared | $25 a month | 300 a month and 200 a day | No |
| Dedicated (your own number) | $100 a month | 1,000 a day (250 a day at first, ramping to 1,000 over the first 14 days), no monthly cap | No |
| + Outbound (writing first) | +$40 a month, dedicated only | Same as the plan; new conversations ramp from 2 a day to 40 a day over 21 days | Yes |
SMS and RCS fallback from the same number is included on every plan, the free trial too. Call forwarding is included on dedicated lines.
- 200 people a month, replies only: the $25 shared line.
- 200 people, with your own number: a $100 a month dedicated line.
- 1,000 people a month, replies only: a $100 a month dedicated line, since the shared line stops at 300 a month.
- Up to 1,000 people a day, including reminders you send first: a $100 a month dedicated line, with the $40 a month Outbound add-on for writing first. The line’s limit starts at 250 people a day and ramps to 1,000 over its first 14 days; the conversations it starts ramp separately, from 2 a day to 40 a day over 21 days.
- Android customers too: any plan. SMS/RCS fallback from the same number is included on all of them.
- More than 1,000 people a day: add another dedicated line.
On Flow, a $25 shared line fits 300 people a month, a dedicated line is $100 a month, and there are no per-message or setup fees. At a limit, a new person is held, not delivered, and people already in conversation keep working. You buy a plan, and the $40 Outbound add-on, yourself in the Flow dashboard under Settings → Usage and billing → Choose a plan. Flow reviews each dedicated line, then sets it up, usually within a day.
Start free on Flow’s iMessage line and price your own volume.
Three ways to price an iMessage API
Per line. You pay a monthly fee for each phone number that sends and receives. The fee is steady, but it does not shrink if few people use the line. Limits move to other places, such as contacts per day or who may write first.
Per message. You pay for each message or segment. Cost rises with volume, and a chatty agent costs more.
Per line, with a cap on people. You pay a monthly fee for a line, and the plan caps how many different people it talks to in a day or a month. Flow does this for iMessage, per account and channel, by UTC calendar day and month. Replies count toward the day’s people limit too, but each person counts once a day however many messages they exchange, so a chatty agent costs the same.
Which is cheaper depends on how many people use your agent and how much each one talks. A busy agent with few people favours a plan with a people cap. A quiet line with many one-message contacts can favour per-line pricing.
What the price does not include
The sticker price is only part of the cost. Check these before you decide:
- Model costs. The LLM your agent calls is almost always a separate bill. On Flow you can bring your own model.
- WhatsApp fees. If you also use WhatsApp, Meta bills its messaging fees directly.
- Who can write first. A cheaper plan may be inbound-only. On Flow, writing first comes with the $40 a month Outbound add-on on dedicated lines, and the conversations it starts ramp from 2 a day to 40 a day over 21 days.
- Fallback and groups. Check which plan includes SMS or RCS fallback and groups. On Flow, SMS and RCS fallback is from the same number and included on every plan, and the agent can reply in groups a dedicated line was added to.
- Ramps. On Flow, Flow reviews a new dedicated line, then sets it up, usually within a day. Its limit of different people starts at 250 a day and ramps to 1,000 over its first 14 days. With Outbound, the conversations it starts ramp separately, from 2 a day to 40 a day over 21 days.
- Compliance. Ask any vendor for its current report and verify that it covers the product and data you plan to use.
How to compare on your own numbers
- Count people, not messages. How many different people will use your agent in a day and in a month? Plans with a people cap care about this.
- Count messages. How many messages will each send? This matters for per-message pricing.
- Decide who writes first. If your agent must start conversations, rule out inbound-only plans.
- List the features you need. Groups, fallback, effects, compliance.
- Price a month. Put real numbers in each company’s plan. Then re-check the pages, because prices change.
If you want to see the fit for your agent, read the guide to building an iMessage agent, then start free on Flow.
Frequently asked questions
How much does an iMessage API cost?
Flow is the best value: a free trial on the shared line for 25 people, $25 a month for 300 people a month on a shared line, and $100 a month for a dedicated line for 1,000 people a day (a new line starts at 250 a day and ramps to 1,000 over its first 14 days). There are no per-message fees, and on a dedicated line writing first comes with the $40 a month Outbound add-on; the conversations it starts ramp from 2 a day to 40 a day over 21 days.
Is there a free iMessage API?
Yes. Flow has a free trial on its shared iMessage line for 25 people, plus a no-account Telegram sandbox and simulated contacts for testing your agent.
Why does a dedicated iMessage line cost more?
A dedicated line is a phone number reserved for your agent, with its own sending identity and reputation. A shared line is used by many businesses at once. A Flow dedicated line is $100 a month.
Do iMessage APIs charge per message?
Flow prices iMessage by line and by people, not by message. Each different person counts once a day and once a month, replies included, so more messages with someone already counted cost nothing extra.
What counts as a person on Flow?
A person is anyone whose messages the agent reads, counted once a day and once a month (UTC calendar day and month; once in total on the free trial). In a group, every member who writes counts; silent members do not. Limits are per account and channel.
Keep reading
All posts: the Flow blog. The Flow docs have the reference.
From reading to building
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