Dev tools · alternatives · 2026

24 alternatives to Cone API

Unified email, calendar APIs

Below are 24 products that do a similar job, ranked by how close each is in meaning and then by launch-day votes. Cone API launched in 2022; newer entries below may have overtaken it.

1
Recal.dev▲365
Resend, but for Calendar & Scheduling. API. SDK. MCP.
2025 · recal.dev · its alternatives →
2
Available▲306
Share your calendar availability right inside of Gmail
2020 · its alternatives →
3
InboxSDK▲508
First usable API to write Gmail Apps for 1B active users
2015 · inboxsdk.com · its alternatives →
4
SavvyCal for iCloud▲293
Scheduling links for iCloud, plus Google, Outlook, Fastmail
2021 · savvycal.com · its alternatives →
5
Astro 3.0▲264
Intelligent inbox and calendar for iOS, Android, Mac & Slack
2018 · its alternatives →
6
HEY Calendar▲360
Bringing magic to calendaring
2024 · apps.apple.com · its alternatives →
7
Meetingbird for Gmail▲333
View your calendar and schedule meetings right from Gmail
2017 · front.com · its alternatives →
8
Mailercloud Email API Platform▲165
1,000+ Emails per Second with 99%+ Deliverability
Mar 2026 · mailercloud.com · its alternatives →
9
CalendarPipe▲155
Create pipes to filter, transform, and sync events between Google Calendar, Outlook, and Apple Calendar. Build visually, describe in plain English, or write code.
Apr 2026 · calendarpipe.com · its alternatives →
10OS
Open-Sourcing InboxSDK (YC S11) – Build Apps in Gmail▲257
Hi HN! We’re Aleem, Chris, Borys, Meichen and Zach from Streak (YC S11) and today we’re open sourcing our InboxSDK https://www.inboxsdk.com, which makes it easy to build apps for Gmail. Over 1.8B users spend their days in Gmail! Having your app built into the Gmail workflow is a better user experience and gives you great user retention. InboxSDK gives you a high-level, declarative API to insert your UI into Gmail without having to directly manipulate the DOM yourself. End users install a browser extension to use your app. The SDK can add UI to multiple areas of Gmail. For example,…
2022 · its alternatives →
11IB
I built Mailhub – A scalable API for sending emails with ease not tears▲104
2024 · mailhub.sh · its alternatives →
12
Timely▲176
Pull your calendar availability in 3 seconds
Jul 2026 · trytimely.co · its alternatives →
13
Unosend▲205
Send transactional + marketing email w/ 99.9% deliverability
Dec 2025 · unosend.co · its alternatives →
14
Mixmax Scheduling Assistant▲183
The ultimate email + calendar productivity suite
2015 · mixmax.com · its alternatives →
15
Astro▲67
AI meets email for Mac, iPhone, and Android
2018 · its alternatives →
16
Simplified Content Calendar & Analytics▲118
Create, plan and publish your social content in one tool
2022 · simplified.com · its alternatives →
17
CalendarPlusAI▲203
Shared calendar no login Collaborate with friends and teams!
2024 · bcalendar.com · its alternatives →
18
Alice▲178
Generate fully blown content calendar with SEO articles
2024 · app.storychief.io · its alternatives →
19
Assistly▲74
Meeting scheduler for email text
2023 · its alternatives →
20
EasyListing▲102
Create, manage, and grow your email list
2025 · its alternatives →
21
OneCal▲125
Synchronise Outlook and Google Calendars
2023 · onecal.io · its alternatives →
22
Simple Email API▲15
2021 · batsign.me · its alternatives →
23
ShadowCal▲95
Sync your Outlook Calendar to Google Calendar
2025 · shadowcal.com · its alternatives →
24
Cronofy API▲69
Unified Calendar API for developers
2015 · cronofy.com · its alternatives →

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Ranked by how close each launch is in meaning, then by votes. Prices were read from each product’s own site when checked and can change. Refine with your own description →