Kimai vs Harvest: which choice reduces costs, secures data and scales with teams in England and the EU? A decision at procurement time affects billing workflows, privacy compliance and developer effort. This guide delivers a clear, updated 2025–2026 comparison, a feature matrix, a practical migration checklist and a simple TCO framework to assess self‑hosting (Kimai) versus SaaS (Harvest).
Quick verdict and decision criteria
Both products cover core time tracking, but the decision depends on four criteria: control, cost predictability, integrations and compliance. Kimai is an open‑source, self‑hosted solution that grants maximal control, modifiability and lower recurring license fees but requires hosting and maintenance. Harvest is a cloud SaaS with polished billing, team reports and native invoicing, trading off vendor dependency for faster onboarding.
- Control and data residency: Kimai favours organisations requiring on‑premises or EU hosting. See GDPR guidance from the European Data Protection Board: EDPB.
- Total cost of ownership (TCO): Kimai shifts costs to hosting, backups and admin time. Harvest charges per‑user SaaS fees and includes hosting, maintenance and support.
- Integrations and workflows: Harvest ships with built‑in invoicing and first‑party integrations. Kimai relies on plugins, the community and API connectors.
- Compliance and security: self‑hosting enables bespoke controls; SaaS can offer strong operational security SLAs.
Key differences at a glance
Licensing and deployment
- Kimai: MIT open‑source license; self‑hosted or managed providers. Official information and downloads at the Kimai website: Kimai.org and source code on GitHub: github.com/kimai/kimai2.
- Harvest: Proprietary SaaS with subscription tiers; hosted by Harvest. Product pages and pricing: getharvest.com.
Billing and invoicing
- Harvest: native invoicing, client billing, expense tracking and recurring invoices built into the UI.
- Kimai: invoicing commonly provided via community plugins or external integrations; suitable for organisations that integrate time data into existing accounting systems.
Integrations and API
- Harvest provides a mature API and official docs: Harvest API v2.
- Kimai exposes REST endpoints and relies on community connectors and third‑party automation (Zapier, native plugins). Zapier lists Harvest and time‑tracking connectors: Zapier Harvest integrations.
Detailed feature comparison
Timers, tracking modes and offline use
- Timers and manual entries: both support timers and manual timesheet entries.
- Idle detection and reminders: Harvest includes native idle detection and reminders in the desktop/web clients. Kimai plugins offer similar behaviour but may require configuration.
- Offline/edge cases: Harvest mobile apps sync when online; Kimai mobile experiences vary by deployment and chosen mobile client.
User roles, access control and team management
- Kimai: flexible role model, fine‑grained permissions via configuration files and plugins; ideal for controlled, role‑specific access.
- Harvest: role model tuned for fast onboarding with team and client roles; centralized admin in the SaaS console.
Multi‑currency, tax and invoicing capabilities
- Harvest: native multi‑currency billing, tax settings and invoice templates.
- Kimai: multi‑currency depends on extensions or exporting time data to an invoicing system.
Mobile and desktop experience
- Harvest: polished iOS and Android apps, plus web timer. Usability ratings and mainstream adoption put Harvest ahead for organisations prioritising ease of use.
- Kimai: web first with community mobile options; performance and UX depend on version and deployment choices.
Comparative matrix (2025–2026 feature snapshot)
| Feature |
Kimai (open‑source) |
Harvest (SaaS) |
| Licensing |
MIT, self‑hosted |
Proprietary subscription |
| Hosting |
On‑prem / cloud (user‑managed) |
Hosted by Harvest |
| Pricing model |
Hosting + maintenance costs |
Per‑user monthly/annual fee |
| Native invoicing |
Limited / plugin |
Yes, built‑in |
| Integrations |
Community + API |
Numerous first‑party + Zapier |
| API |
REST, community docs |
Official API v2 (stable) |
| Mobile apps |
Community / web |
Official iOS & Android |
| GDPR / data control |
Full control, easier compliance for EU hosting |
Data processed by Harvest; rely on vendor DPA |
| Scaling |
Depends on host resources |
Scales with provider infrastructure |
| Support |
Community, paid providers |
Official support tiers |
Sources and vendor docs for attributes: Kimai docs: Kimai docs; Harvest: Harvest product pages.
Migration: moving data from Harvest to Kimai (practical checklist)
Step 1: Audit current Harvest data
- Export time entries, projects, users and invoices from Harvest using the UI or API. Harvest export documentation: Harvest Help Center.
- Verify CSV/JSON completeness and note custom fields used for billing or cost codes.
Step 2: Prepare the Kimai environment
- Provision hosting (Linux + Nginx/Apache, PHP 8+, MySQL/MariaDB or PostgreSQL). Follow official requirements: Kimai installation.
- Configure backups, TLS, firewall rules and monitoring.
- Map Harvest fields to Kimai entities (projects, activities, users, billable flags).
- Use the Kimai import plugin or write a script that posts to Kimai’s REST API. Test with a subset before full import.
Step 4: Reconcile invoices and billing history
- Maintain a read‑only archive of Harvest invoices for financial audit. If invoicing will be done in Kimai, migrate invoice line items and client data carefully.
Step 5: Validate and go live
- Run parallel tracking for 1–2 weeks, reconcile totals and user feedback. Ensure GDPR data records and deletion requests are handled per policy.
TCO framework: self‑hosting vs SaaS (example scenarios)
- Scenario assumptions: 25 users, standard UK cloud hosting, 3 years horizon.
Costs to model:
1. SaaS subscription: Harvest business tier at per‑user rates (check current pricing at Harvest pricing).
2. Self‑hosted Kimai: server instances, backups, SSL, sysadmin hours (estimate 2–5 hours/month), plugin premium fees, security updates.
Example quick math (indicative):
- Harvest: £12/user/month * 25 * 36 months = £10,800 (includes hosting/support).
- Kimai: VM £40/month + backups £15 + sysadmin (£60/hr * 3 hrs/month) = £40+15+180=£235/month → 36 months = £8,460 + contingency for upgrades/plugins ≈ £10,500.
Interpretation: numbers converge when sysadmin cost and plugin support are accounted for. Harvest simplifies operations; Kimai can be cheaper long term for larger teams or when leveraging existing IT staff.
Security, GDPR and operational controls
- Data residency: Kimai allows EU‑based hosting, easing GDPR obligations where data residency matters. Harvest maintains DPA options; confirm vendor subprocessors and transfer mechanisms.
- Patch management: self‑hosting requires a patch cadence and monitoring. SaaS vendors typically handle patching and incident response.
- Backups and retention: self‑hosted systems must implement retention policies; Harvest provides vendor retention but the organisation must confirm export processes for audits.
Useful compliance resources: GDPR overview at gdpr.eu and EDPB guidance: edpb.europa.eu.
- Kimai scales with database tuning, PHP workers and caching; benchmark by simulating concurrent timers and reporting loads. Recommended stack tweaks: opcode caching, connection pooling and a dedicated read replica for heavy reporting.
- Harvest abstracts infrastructure concerns; performance SLAs depend on the vendor. For global teams, confirm CDN, regional availability and mobile sync behaviour.
Authoritative resources on integration patterns and benchmarking: Zapier automation patterns: Zapier Learning.
- Bulk imports should run off‑peak and in transactions to avoid partial states.
- Validate API rate limits for Harvest when exporting large datasets.
Practical examples and use cases
- Small consultancy (5 users): Harvest typically reduces time to value due to zero maintenance and built‑in invoicing.
- Mid‑sized agency (30–100 users) with custom reporting needs and EU data residency requirements: Kimai with managed hosting or hybrid architecture often provides better cost control and compliance.
Common questions
Is Kimai suitable for billing clients directly?
Yes, but invoicing typically requires plugins or external accounting integration. For organisations that require immediate, polished invoicing workflows, Harvest includes native invoicing and billing workflows.
Can Harvest export all data for legal or audit purposes?
Harvest provides export and API access for time entries, invoices and reports. Verify retention windows and export formats in vendor policy: Harvest Help Center.
Does Kimai meet GDPR requirements?
Kimai itself is a tool; GDPR compliance is achieved through hosting choices, data handling policies and technical controls. Host the application in the EU, implement access logging and a DPO process to align with GDPR obligations.
How difficult is it to maintain Kimai?
Maintenance complexity depends on internal skillsets. Routine tasks include PHP and dependency updates, database backups, security monitoring and plugin compatibility checks.
Conclusion
Selecting between Kimai vs Harvest depends on organisational priorities. Choose Kimai for maximal control, EU data residency and flexible customisation. Choose Harvest for speed of deployment, polished billing, and vendor‑managed operations. Apply the TCO checklist and the migration steps above to quantify costs, test a pilot and validate compliance before a full migration.
Further technical reading and vendor documentation for next steps:
- Kimai documentation: https://www.kimai.org/documentation/
- Harvest product and API: https://www.getharvest.com
- GDPR basics and EDPB guidance: https://gdpr.eu
