RescueTime vs SimplyBook.me vs Sling: Which Is Right for You in 2026?
These three share the 'scheduling' label but almost never compete for the same purchase decision. RescueTime schedules nothing on its own; it passively tracks…
freemium subscription (Solo and Team tiers) · From Free (Lite); paid Solo Focus plan from $7/month billed annually ($84/year)
Best for: Knowledge workers and remote teams who want automatic, non-manual tracking of app and website usage to diagnose where their time actually goes.
Freemium per-user subscription · From Free (up to 30 users); paid plans from $2/user/month
Best for: Restaurants, retail, healthcare, and other shift-based employers that need to build staff schedules, track hours, and manage labor costs.
At a Glance
RescueTime
SimplyBook.me
Sling
Primary category
Scheduling
Scheduling
Scheduling
Rating
Not documented
Not documented
Not documented
Pricing model
freemium subscription (Solo and Team tiers)
freemium
Freemium per-user subscription
Starting price
Free (Lite); paid Solo Focus plan from $7/month billed annually ($84/year)
Free plan available; paid plans from $8.25/month
Free (up to 30 users); paid plans from $2/user/month
Free plan
Yes
Yes
Yes
Free trial
Yes
Not documented
Not documented
Platforms
Mac, Windows
iOS, Android
Web, iOS, Android
Team collaboration
Not documented
Not documented
Not documented
AI features
Not documented
Not documented
Not documented
Public API
Not documented
Yes
Not documented
Standout Differences
Three different calendars, not three competitors
RescueTime tracks your own computer usage automatically, SimplyBook.me manages bookings coming in from customers, and Sling manages shifts going out to employees. A business could realistically license all three at once without any overlap in what each one does.
RescueTime, SimplyBook.me, Sling
RescueTime is passive, the other two are active scheduling tools
RescueTime requires no manual scheduling input at all; it monitors app and website activity in the background and reports on it. SimplyBook.me and Sling, by contrast, are both built around actively creating and managing a calendar of bookings or shifts.
RescueTime
SimplyBook.me is the only one built for external customers
SimplyBook.me's client management, payments, and marketing automation are aimed at the people booking your services, not your internal staff. Neither RescueTime nor Sling is designed to let outside customers reserve a time slot.
SimplyBook.me
Sling has the most aggressive free tier for teams
Sling's free plan covers up to 30 users before paid pricing kicks in at $2/user/month, making it accessible for small shift-based teams from day one. SimplyBook.me also has a free plan, while RescueTime's free 'Lite' tier is scoped to an individual rather than a team.
Sling, SimplyBook.me, RescueTime
Feature-by-Feature
Core Job
Feature
RescueTime
SimplyBook.me
Sling
Automatic personal time/activity tracking
Available
Unavailable
Unavailable
Client-facing online appointment booking
Unavailable
Available
Unavailable
Employee shift scheduling
Unavailable
Unavailable
Available
Labor cost / staff hours tracking
Unavailable
Not documented
Available
Pricing & Plans
Feature
RescueTime
SimplyBook.me
Sling
Free plan available
Available
Available
Available
Per-user paid pricing
Not documented
Not documented
Available
Dedicated team/multi-seat tier
Available
Not documented
Available
Pricing Compared
Starting price reflects the lowest paid tier, not the full cost for every team size or usage level.
RescueTime
Lite — Free n/a
Solo Focus — $7/month billed annually ($84/year) or $9/month monthly or annual
Solo+ — $12/month billed annually ($144/year) or $15/month monthly or annual
Team Focus — $10/month per user billed annually ($120/year) or $12/month monthly or annual
Team+ — $16/month per user billed annually ($192/year) or $18/month monthly or annual
SimplyBook.me
Free — $0 monthly
Basic — From $8.25/month monthly
Standard — Up to $13.90/month monthly
Premium — Up to $59.90/month monthly
Enterprise — Custom contact sales
Sling
Free — $0 n/a
Premium — $2/user/month monthly
Business — $4/user/month monthly
Pros & Cons
RescueTime
Pros
Fully automatic tracking requires no manual timers or check-ins
Free Lite tier available for basic automatic tracking and reporting
Timesheets add-on supports billable client work for freelancers and agencies
Remains independently operated with a long operating history since 2006
Cons
Premium features (Focus and Timesheets) require a paid subscription
Team pricing is per-user, which can add up for larger teams
Small company size (roughly 10-15 employees) may limit support and feature velocity
Passive tracking requires installing and running background software on all devices
Some advanced project/billing features are gated behind the higher Solo+ or Team+ tiers
SimplyBook.me
Pros
Generous free plan makes it accessible for solo professionals starting out
Wide range of add-ons lets businesses customize functionality without switching platforms
Multilingual booking pages and support suit businesses with international clients
Marketing tools like gift cards and loyalty points go beyond basic scheduling
Scales from solo professionals up to multi-location enterprise businesses
Cons
Interface can feel dated compared to newer scheduling tools like Calendly
Many advanced features are gated behind paid add-ons, which can increase total cost
Enterprise pricing is not publicly listed and requires contacting sales
Learning curve exists for businesses that want to configure the full add-on ecosystem
Exact founding year is reported inconsistently across sources (2009 launch versus 2011 rebrand)
Sling
Pros
Free tier supports up to 30 users, generous compared to most scheduling competitors
Drag-and-drop scheduling and shift swapping are widely praised for ease of use
Time tracking with geofencing adds accountability for on-site clock-ins
Built-in messaging removes the need for a separate team communication tool
Now backed by Toast, giving it more resources following the 2022 acquisition
Cons
Deeper payroll and HR features generally require external integrations
Some advanced reporting is reserved for the Business tier rather than Premium
Company size and standalone revenue are not disclosed separately from parent company Toast
Primarily optimized for shift-based hourly work, less suited to salaried or project-based teams
Since the Toast acquisition, some users report a stronger product focus on food service and hospitality
Use Cases
Choose RescueTime: Knowledge workers and remote teams who want automatic, non-manual tracking of app and website usage to diagnose where their time actually goes.
Choose SimplyBook.me: Service-based businesses (salons, clinics, consultants, tutors) that need a public booking page where clients can self-schedule and pay.
Choose Sling: Restaurants, retail, healthcare, and other shift-based employers that need to build staff schedules, track hours, and manage labor costs.
RescueTime
Remote worker productivity tracking — Remote employees and freelancers use RescueTime's automatic tracking and Productivity Pulse to understand and improve how they spend their workday.
Deep work and focus enforcement — Knowledge workers use FocusTime to block distracting sites and apps during scheduled deep-work sessions.
Billable client time tracking — Consultants and agencies use the Timesheets add-on to track billable hours by client and project without manual timers.
SimplyBook.me
Solo service professional scheduling — Independent consultants, tutors, or therapists use the Free or Basic plan to accept online bookings without hiring administrative staff.
Salon and wellness studio management — Salons and studios use staff-based booking, payment processing, and marketing add-ons to manage a growing client base.
Multi-location and franchise booking — Healthcare networks, universities, and franchise businesses use the Enterprise plan to centralize booking across many locations.
Sling
Multi-location shift scheduling — Businesses with multiple locations build and manage shift schedules for hourly staff from one central platform.
Healthcare and fitness staff scheduling — Clinics, gyms, and wellness businesses coordinate shift coverage and time-off requests for part-time and hourly staff.
Labor cost management — Operations managers use real-time labor cost forecasting to keep shift schedules within a weekly budget.
Frequently Asked Questions
Can I use RescueTime, SimplyBook.me, and Sling together?
Yes, and there's no functional overlap that would make it redundant. RescueTime tracks your own computer usage, SimplyBook.me handles customer-facing appointment booking, and Sling handles internal staff shift scheduling. A service business could run all three simultaneously for entirely different purposes.
Which of these is cheapest for a small service business?
For staff scheduling, Sling is free for up to 30 users and only $2/user/month after that. For customer bookings, SimplyBook.me has a free plan and paid plans starting at $8.25/month. Which is 'cheaper' depends on whether you need to schedule customers, staff, or both.
Does SimplyBook.me replace Sling for managing employee shifts?
No. SimplyBook.me is built for client-facing appointment booking, payments, and marketing automation, not for building employee work schedules or tracking labor costs. Sling is the purpose-built tool for shift-based staff scheduling.
Is RescueTime useful for a team, or just individuals?
RescueTime offers both a Solo Focus plan for individuals and a Team tier, so it can be deployed across a team. That said, its job is monitoring personal app and website usage for focus insights, not building schedules the way SimplyBook.me or Sling do.
Which tool actually tracks employee hours for payroll purposes?
Sling is designed around tracking staff hours and labor costs alongside shift schedules. RescueTime tracks time spent in apps and websites for personal productivity insight, not clock-in/clock-out hours for payroll, and SimplyBook.me's pricing summary doesn't document payroll-style hour tracking.