ComparisoniMessage API5 min read
Flow vs Photon: why Flow wins
Flow vs Photon for iMessage: see why Flow is the better choice for AI agents, with a sourced feature table and plans side by side. Updated October 2026.
The short answer
Flow is the stronger value for AI agents on iMessage. Start free with 25 people, support 300 people a month on a $25 shared line, then scale to a dedicated line for $100 a month. Your same agent also works on WhatsApp, Telegram and MCP, with signed webhooks retried for three days.
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.
Flow and Photon feature by feature
Flow first. Every cell links to the page it came from, and where we did not find something the table says to check with the provider.
| Feature | flow.engineer | Photon |
|---|---|---|
| Sends iMessage (blue bubbles) | Yes. A US number, shared or dedicated, with blue-bubble replies | Yes. Managed shared and dedicated lines are listed1 |
| WhatsApp and Telegram | Both, through the same API | Both, through Spectrum2 |
| Webhook signing and retries | HMAC-SHA256 signed; retried for 3 days; ordered per conversation; replayable event log3 | HTTP webhooks are documented; check Photon for signing and retry details2 |
| 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 | Free plan: up to 10 users1 |
| 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 | Free for up to 10 users; Pro $25 a month for up to 100; dedicated Business line $250 a month1 |
| 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 | Plan user limits: 10 free, 100 Pro and Business unlimited with Auto Scale1 |
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.
Why Flow
- More people before you pay. Flow’s free trial on the shared line covers 25 people. Photon lists 10 users on its free tier.
- More room to grow for $25. Flow’s $25 shared line is designed for 300 people a month and 200 a day. Photon lists $25 a month for up to 100 users on Pro.
- A lower-cost dedicated route. A Flow dedicated line is $100 a month, for 1,000 people a day (a new line starts at 250 a day and ramps to 1,000 over its first 14 days). Photon lists its Business dedicated iMessage line at $250 a month.
- One agent, more places. Flow puts the same agent on iMessage, WhatsApp, Telegram and MCP, with a hosted messaging MCP server and CLI.
- Webhooks your production agent can depend on. Flow signs events with HMAC-SHA256, retries them for three days, delivers in order per conversation and keeps a replayable event log.
Put your agent on iMessage with Flow, free to start.
Build, test and scale in one place
Flow gives your team one messaging layer from the first sandbox test to a live iMessage line. The same agent, tools and delivery model work across iMessage, WhatsApp, Telegram and MCP, so new channels do not mean a new integration.
What to plan for
- Choose based on the people you expect each month: Flow starts free for 25 people, then supports 300 people a month for $25 a month.
- Writing first: the $40 a month Outbound add-on on Flow dedicated lines, within warm-up limits. Shared lines are reply-first.
- If native mini apps, custom group controls or voice calling are central to your product, confirm the exact requirements and plan before choosing.
Keep reading
For the whole market, read the best iMessage API and iMessage API pricing compared. To see how Flow works on iMessage, read Flow on iMessage: features, pricing and limits and Build an iMessage AI agent.
Frequently asked questions
Why choose Flow over Photon?
Flow gives AI-agent teams a more compelling price-to-reach path: free for 25 people, 300 people a month for $25 a month and a dedicated line for $100 a month. The same agent also works across iMessage, WhatsApp, Telegram and MCP.
How much does Photon cost compared with Flow?
Photon lists a free plan for up to 10 users, $25 a month for up to 100 users and a $250 a month dedicated Business line. Flow is free for 25 people, $25 a month for 300 people a month, and $100 a month for a dedicated line.
Can I start free with Flow?
Yes. Flow’s free trial on the shared iMessage line covers 25 people. Customers text first on shared lines.
Does Flow support WhatsApp, Telegram and MCP?
Yes. Flow lets one agent work across iMessage, WhatsApp, Telegram and a hosted messaging MCP server, from one codebase.
Can Flow write first on iMessage?
Writing first comes with the $40 a month Outbound add-on on dedicated Flow lines, within warm-up limits. Shared lines are reply-first.
Keep reading
All posts: the Flow blog. The Flow docs have the reference.
From reading to building
Your agent, on iMessage and everywhere else.
Flow gives your agent an iMessage line, and the same code answers on WhatsApp and Telegram and works as an MCP server and CLI. See how it works on iMessage.
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