A one-person consulting stack: four jobs, $0 to $336 a year
A solo consultant needs four things from software: somewhere to take bookings, a way to invoice, a place for the client list, and a way to stay in touch. Every one of those jobs has a genuinely free answer right now. Here is the whole stack — and the specific milestones at which each piece becomes worth paying for.
The stack at $0
| Job | Free answer | What it does | The catch |
|---|---|---|---|
| Bookings | Calendly Free | 1 event type, 1 calendar, unlimited bookings | One meeting format only |
| Invoicing | Wave Starter | Unlimited invoices, estimates, bookkeeping records | 2.9% + $0.60 per card payment |
| CRM | systeme.io Free or a spreadsheet | 2,000 contacts, 1 funnel, unlimited email sends | Rough product; 1 automation rule |
| Kit Free | 10,000 subscribers, unlimited sends | No automations or sequences |
Why this combination and not another
The free-tool market for solo operators is full of traps, and this stack avoids the three biggest ones.
Calendly Free is complete for one meeting format — and that is the honest test: if you run a free intro call, it does the whole job. The day you add a paid consultation as a second format, Standard at $10 a seat a month ($120 a year) is the upgrade, and because a solo consultant is one seat, that is the entire cost. The tier detail is in Calendly pricing explained.
Wave Starter is free because Wave is paid by processing — 2.9% plus $0.60 per card transaction. That is a fine deal, and it is free if your clients pay by bank transfer, which is the case for most consulting invoices above a few thousand dollars. At ten $800 invoices a month all paid by card, the fee is $2,856 a year — so the real decision is not "which invoicing tool" but "how do clients pay". The arithmetic is in the cheapest way to invoice clients, and the alternative's published prices — FreshBooks at $23 with a five-client cap — are in Wave vs FreshBooks.
systeme.io Free covers 2,000 contacts with zero platform fee — unusual, because most free plans either cap contacts hard or take a percentage. Its interface is the rough edge you accept. If your client pipeline is still small enough for a spreadsheet, the spreadsheet is also a correct answer; the graduation path is in from spreadsheet to CRM.
Kit Free carries 10,000 subscribers without automations. For a consultant sending a monthly note, that is years of headroom on the largest free ceiling in the category. When you need a welcome sequence, Creator at $33 a month is the first real spend in this whole stack.
The paid version of the same stack
If every piece upgrades at the moment it must, the all-in cost for a working solo consultant is:
- Calendly Standard, 1 seat, annual: $120/yr — the second meeting format arrives
- Wave Pro, annual: $190/yr — only worth it past ~32 card payments a month; otherwise Starter stays free
- Kit Creator: $396/yr — the welcome sequence arrives, or the recommendation network matters
- systeme.io Startup: $204/yr — the second funnel, or 2,000 contacts exceeded
Fully upgraded: $910 a year. Realistically a consultant upgrades two of the four in year one, landing around $336-$516. That range — not $150 a month for an "all-in-one consultant OS" — is what this stack actually costs, and every number in it is vendor-published with a date.
The two milestones that matter
- The second meeting format. This is the first real money in the stack: $120 a year, and worth every cent, because a paid consultation you cannot book online is a phone call, and phone calls do not scale.
- The first automated follow-up. The moment a client would benefit from a sequence — onboarding, payment reminders, a check-in three weeks after delivery — the free tier of whichever tool you chose stops being enough. This is also the moment to check whether your pieces still fit together; automations across four free tools are where the integration tax starts, and it is the argument for consolidating into a bundle. Whether the bundle is worth it is exactly the bundle-versus-parts question, applied to a different vendor.
What we deliberately left out
A website builder — because a consultant's site is one page and a booking link, and every tool in this stack gives you a page. Project management — because one person with a deadline sheet does not need a workspace, and the free options when you do are covered in the best free project management tool. And payroll, accounting and taxes — because those depend on your country and are not a software decision first.
What we cannot verify
Every price here was read from the vendor's own pricing page on October 23, 2026, in USD, and each individual claim has a dedicated article with its own verification note. We have not run this stack as a combined system, so integration friction between the four tools is unverified by us. Wave's card-fee assumption reverts to $0.60 after Pro's ten free transactions per month — that detail is Wave's page's, and the reversion is our reading. Calendly's monthly-billed prices are derived from its own percentage badges, not quoted. See How We Test for what we check and what we label.