Best Open Source Time Tracking 2026: The Minimalist Guide

TL:DR: For 2026, BareStack is the best open source time tracking tool if you bill by the hour, because it runs alongside projects, CRM and invoicing under one AGPL codebase and costs $0. Kimai is the runner-up for teams that need timesheet approvals and per-activity rates, while ActivityWatch is the pick when you want automatic local tracking and never type an hour at all. The trade-off is honesty about scope: BareStack logs hours and shows billable totals, but it does not push logged hours into an invoice automatically, so you copy the total across by hand.

What best open source time tracking 2026 really means

"Best" gets used to mean two incompatible things in this space, and most listicles never say which one they are selling.

The first meaning is a timer. You start it, you stop it, and at the end of the week you see where the time went. Nobody is invoiced, nobody approves anything, and the output is a chart you use to change your own behaviour.

The second meaning is a billable-hours system. The number has to survive contact with a client: attributable to a project, reportable, defensible in a dispute, and reusable in a document you send to get paid. That is a different engineering problem.

So the honest criteria are five questions:

1. Can you record time against a specific client and project?
2. Can you get that time back out in a form a client will accept?
3. Where does the data live, and who else can read it?
4. What does the free tier actually withhold?
5. What does running it cost you monthly in money and attention?

A tool that is superb at question 1 and useless at question 2 is not "the best time tracker", it is the best tool for a job you do not have. Price is rarely the deciding factor: Toggl Track's Starter plan runs about $9 per user per month, and Harvest's paid seats start at $9 per seat per month on monthly billing, per Harvest's own pricing page. Neither is expensive. Both are recurring, and both are why people end up on a page like this.

The best open source time tracking tools compared in 2026

Five tools, all open source, all free to run. Read this first, then skip to whichever one matches your situation.

The "paid starts at" column is empty for four of five tools because there is no paid tier to start at. And these tools are not interchangeable: picking the wrong one is the actual expensive mistake in this category.

Option 1: BareStack, the unified dashboard for billable hours

Most freelancers do not just need a timer. They need to get paid, and they are already running a CRM, a project list and an invoicing habit. BareStack is an AGPL-licensed business workspace that puts time tracking in the same app as projects, CRM and expenses, so the hours you log sit next to the client who owes you money.

What the module does, concretely: you pick a project, enter hours, mark the entry billable, and the page totals your hours for the week and your lifetime billable hours. That is the whole feature, and it is the one that matters if you invoice from a spreadsheet today. The value is not a clever timer, it is that the hours live in the same database as the project and the invoice, so nothing is exported and re-imported at month end.

Where it is honest about its limits. BareStack does not convert logged hours into invoice line items automatically. There is no button that reads your time entries and fills out an invoice. If you need that specific automation, that is a real gap, and Kimai does it better. What you get instead is proximity: the number you need is on screen next to the client you are billing.

Pick it if you bill hourly and want one login instead of a monthly fee for a timer plus a separate tool for everything else. Skip it if you need approval workflows, want the invoice to build itself from the timesheet, or run a team of fifty.

Option 2: Kimai, the feature-rich timesheet specialist

Kimai has been the heavyweight in this space for years, and it is a genuinely different product from everything else here. It is a timesheet system, not a timer. It models customers, projects and activities, and it attaches a rate to each activity, which is how consulting shops bill different rates for different work on the same project.

What sets it apart are the capabilities a growing team actually needs: export to PDF, ODS, XLSX, HTML and CSV, invoice generation directly from selected projects, a JSON REST API, and a detailed role concept so users only see what they are permitted to see, as documented on kimai.org. Kimai is AGPL-3.0, actively maintained, and offers hosted cloud alongside self-hosting. The trade-off is configuration depth: setup takes real decisions about fields you may not care about, and the interface is utilitarian in a way a modern React app is not.

Pick it if several people submit time, you need different rates per activity, or invoices must come out of the system. Skip it if you are one person who just needs a number for an invoice.

Option 3: ActivityWatch, the automated privacy-focused tracker

ActivityWatch answers a different question. Instead of asking what you should log, it logs what happened. It runs locally, watches the active window, and records which application was in focus and for how long. Nothing leaves your machine. It is MPL-2.0 licensed and has close to 19,000 GitHub stars, which tells you how many people want this.

This is the tool for "I feel like I worked ten hours and only got two hours of code done". A week of ActivityWatch data answers that precisely, including the uncomfortable part about how much of the week went to chat and email. For developers there are editor plugins covering VS Code, Vim and JetBrains.

The trade-off is that this data is not billable. ActivityWatch has no concept of a client, a rate or an invoice. Turning its timeline into something a client will accept means mapping window titles to projects by hand and transcribing the result. It is desktop-bound by design, which is exactly why the privacy story is strong.

Pick it if you want an accurate picture of your own attention. Skip it if the output has to be defensible to a client.

Option 4: Super Productivity, the developer-centric task planner

Super Productivity is a to-do list with a timer bolted on, aimed at people whose day is a queue of tickets. You pull tasks in from Jira, GitLab or GitHub, press play on one, and it logs the time locally and syncs the worklog back to the tracker. It is MIT licensed, popular at over 22,000 GitHub stars, and works offline, which matters more than it sounds like it should.

The trade-off is that it is not a business tool. There is no invoicing, no CRM, no client records. It is a personal productivity app that happens to be very good at logging time against issue-tracker tickets, and its interface is built for developers.

Pick it if your work already lives in Jira, GitLab or GitHub tickets. Skip it if you need to bill anyone.

Option 5: Solidtime, the modern self-hosted alternative for teams

Solidtime is worth knowing about because it is the newest of the group and it fixes the complaint people have about Kimai. It is AGPL-3.0, claims around 8,900 GitHub stars, reports over 1,000 self-hosted servers, and is fully bootstrapped, so there is no venture-funded roadmap to worry about, per their own site. The desktop app does automatic activity tracking with idle detection and stays local until you choose to log the time, delivering ActivityWatch's promise inside a tool that also has a team-facing web app.

The appeal is a modern interface and a hosted option without managing the infrastructure, which is the gap between Kimai's depth and everyone else's simplicity. It is younger than the others, so the feature set is still filling out.

Pick it if you want Kimai's deployment flexibility with an interface that does not feel like 2010. Skip it if you need a deep plugin ecosystem or built-in invoicing.

The hidden cost of "free" cloud trackers

You could reasonably ask why any of this matters when Toggl and Harvest both have free tiers, and the answer is the business model rather than the price tag.

Free tiers are lead generation for the paid tier. They are real and often generous, and they are also engineered so that the moment your work changes shape you need the upgrade. Harvest's free plan is limited in seats and projects, and its paid plans climb to $14 per seat per month on monthly billing, per Harvest's pricing page. That is not a scandal, it is a business whose incentives point away from you.

Your time data is genuinely revealing. It shows who you work for, what you charge, how fast you work, and how much of your week is billable. A vendor holding that on servers you do not control can lose it in a breach, sell it in an acquisition, or change the terms. The open-source alternative is not that the data becomes magic, it is that the data becomes yours, in a database you can dump, move, back up and delete.

Self-hosting costs real money, just less of it. The licence fee is zero, the VPS is not. A basic server runs about $4 to $6 a month for as many users as you like. A 15-person team on a $9 per seat plan is $135 a month for tools one small box could serve.

How to choose (the decision tree)

Answer these in order and stop at the first yes.

• Do you need to invoice a client from the hours? Yes: BareStack if you want hours sitting next to the client record, Kimai if you want the system to generate the invoice. No: keep reading.
• Is the output for one person's own insight rather than a client? ActivityWatch, without hesitation. It is the only tool here that is accurate about time you did not know you were spending.
• Do you work in Jira, GitLab or GitHub tickets? Super Productivity. It is built for exactly that and syncs worklogs back.
• Do you need multiple people to submit and approve time? Kimai. The role model and export formats exist for that reason.
• Do you want a modern interface and a hosted option without running a server? Solidtime.
• Are you technical enough to run a VPS, or willing to learn? If yes, self-host anything here and your marginal cost per user is zero. If no, ActivityWatch and Super Productivity are desktop installs that need no server at all.
• Are you a solo operator who already keeps clients somewhere and just wants hours next to invoices? BareStack, and stop reading. That is the realistic answer for most people who land on this page.

Integrating with the rest of your stack

Time tracking is rarely the whole problem, and where the hours go next matters more than how you recorded them.

Hours into invoices. BareStack keeps hours, projects and invoices in one database, which removes the export-and-import step for a small operation, though you still transfer the total yourself. If invoicing is the primary workflow, the invoicing guide covers tools that do this natively, and Kimai generates invoices directly from timesheets.

Hours alongside projects. Time tracking gets abandoned because of tab switching, not the timer. When hours live in the same app as the project they belong to, logging stops being a chore, which is the argument for keeping your stack small.

Hours you actually own. The point of self-hosting is that the data leaves with you. If you are weighing that decision generally, the data ownership guide and the self-hosting walkthrough are the follow-ups. See also why open source beats SaaS long term, why time tracking apps are overengineered, the comparison hub and the FAQ.

Bottom line

BareStack is the best open source time tracking tool in 2026 for a freelancer who bills by the hour, because the hours sit in the same free, AGPL-licensed app as the client, the project and the invoice, and nothing about it charges per seat. Kimai is the right answer the moment you need approvals, per-activity rates, or invoices generated from timesheets. ActivityWatch is the right answer when the question is where your attention actually went, and it will never invoice anybody.

Take the timer off your monthly bill and keep the hours.

FAQ

What is the best open source time tracking tool in 2026?

BareStack is the best open source time tracking tool in 2026 if you bill clients by the hour, because it is free, AGPL-licensed, and keeps time entries next to your projects, CRM and invoices in one place. Kimai is the better choice for teams needing timesheet approvals, per-activity rates, or invoices generated from the timesheet. If you only want to understand your own habits, ActivityWatch does that automatically and locally.

Is open source time tracking actually free?

The software is free under licences like AGPL-3.0, MPL-2.0 and MIT, and several of these tools have no paid tier at all. What you pay for is hosting: a basic VPS runs roughly $4 to $6 a month, and some tools run entirely on your own machine for nothing. That holds up against commercial plans like Toggl Track's Starter tier at about $9 per user per month.

Can I generate invoices from open source time tracking tools?

Some of them. Kimai generates invoices directly from selected projects and time. BareStack keeps hours and invoices in the same database so the number is on screen when you build the bill, but it does not auto-fill the invoice from your time entries. ActivityWatch and Super Productivity have no invoicing features, so you would export the data and build the invoice elsewhere.

Is my data safe with self-hosted time tracking?

Your data is as safe as your backups, which is both the risk and the advantage. You trade a vendor's security practices for your own, so automated backups matter and a managed database removes most of the difficulty. The upside is real: nothing is sold, nothing is aggregated into a profile of your business, and a vendor breach cannot leak it.

Do these time tracking tools work offline?

ActivityWatch and Super Productivity are desktop applications and work fully offline because everything stays on your machine. Web-based self-hosted tools such as BareStack, Kimai or Solidtime need a connection to reach the server, though some offer temporary offline caching as progressive web apps.

How much does self-hosting really cost compared to a paid SaaS tracker?

A single VPS hosting one of these tools costs roughly $4 to $6 a month regardless of how many people use it. A five-person team on a $9 per seat plan pays about $45 a month, and a fifteen-person team pays about $135 a month for the same functionality. Self-hosting costs setup time and backup responsibility instead, plus the small server.

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Photo by Samantha Gades on Unsplash

Photo by Andrew Neel on Unsplash

Sources

• Kimai, open source time tracking for project-driven teams
• ActivityWatch, free and open-source automatic time tracker
• Super Productivity, open-source deep work task manager
• Solidtime, open source time tracking for teams
• Harvest pricing plans, free tier and per-seat costs