Quick answer
The best open source quotation and estimate software for most small businesses is InvoicePlane, with InvoiceShelf and Dolibarr ERP CRM as strong alternatives. Verified 16 October 2026.
A quotation or estimate is the offer you send before the work starts. Good software lets you turn an accepted quote into an invoice without retyping. Several free invoicing and ERP tools handle this well.
We write for small businesses, freelancers and growing teams, not large enterprises. Every tool below was checked on GitHub for license, archive status and recent activity, and prices are never quoted because they change. Our picks are based on each project's documentation and repository data, not on hands-on benchmarks, so always try a tool with sample data first. This is general information, not tax, legal or accounting advice.
Top picks at a glance
- InvoicePlane: Quotes that become invoices.
- InvoiceShelf: Estimates with invoicing.
- Dolibarr ERP CRM: Commercial proposals.
What to look for in quotation and estimate software for a small business
- Quote to invoice. Conversion should keep line items and prices intact.
- Branding and PDF. Quotes should look professional and export to PDF.
- Acceptance and expiry. Expiry dates and status prevent old quotes being honored by mistake.
- Tax and discounts. Check discount and tax handling match how you quote.
- Project health and license. Choose a project that is not archived, has recent releases and a real open source license. Check the LICENSE file, not just the website.
Comparison table: best open source quotation and estimate software
| Tool | Best for | License | Stack | GitHub stars | Repo updated |
|---|---|---|---|---|---|
| InvoicePlane | Quotes that become invoices | MIT | PHP | 3,208 | Oct 2026 |
| InvoiceShelf | Estimates with invoicing | AGPL-3.0 | PHP (Laravel), Vue | 1,857 | Oct 2026 |
| Dolibarr ERP CRM | Commercial proposals | GPL-3.0 | PHP, MySQL/MariaDB/PostgreSQL | 7,732 | Oct 2026 |
| ERPNext | Quotations linked to sales orders | GPL-3.0 | Python (Frappe), MariaDB | 40,232 | Oct 2026 |
| IDURAR ERP CRM | Quotes and invoices on Node.js | AGPL-3.0 | Node.js, React, MongoDB | 8,878 | Aug 2026 |
| LedgerSMB | Quotations in double-entry accounting | GPL-2.0 | Perl, PostgreSQL | 570 | Oct 2026 |
Stars and update dates are a snapshot from 16 October 2026 and change daily. They show activity, not quality.
The 6 best open source quotation and estimate tools, reviewed
1. InvoicePlane
Best for: Quotes that become invoices
License: MIT · Stack: PHP · GitHub: 3,208 stars, repo updated Oct 2026
InvoicePlane manages quotes and invoices together so you can convert an accepted quote into an invoice.
Source on GitHub · Official website
2. InvoiceShelf
Best for: Estimates with invoicing
License: AGPL-3.0 · Stack: PHP (Laravel), Vue · GitHub: 1,857 stars, repo updated Oct 2026
InvoiceShelf includes estimates alongside invoices and expenses in a modern interface.
Source on GitHub · Official website
3. Dolibarr ERP CRM
Best for: Commercial proposals
License: GPL-3.0 · Stack: PHP, MySQL/MariaDB/PostgreSQL · GitHub: 7,732 stars, repo updated Oct 2026
Dolibarr handles commercial proposals, orders and invoices in one flow.
Read our full guide to Dolibarr ERP CRM · Source on GitHub · Official website
4. ERPNext
Best for: Quotations linked to sales orders
License: GPL-3.0 · Stack: Python (Frappe), MariaDB · GitHub: 40,232 stars, repo updated Oct 2026
ERPNext turns a quotation into a sales order and invoice, tied to stock and accounting.
Read our full guide to ERPNext · Source on GitHub · Official website
5. IDURAR ERP CRM
Best for: Quotes and invoices on Node.js
License: AGPL-3.0 · Stack: Node.js, React, MongoDB · GitHub: 8,878 stars, repo updated Aug 2026
A JavaScript ERP/CRM that includes quotes and invoices.
Read our full guide to IDURAR ERP CRM · Source on GitHub · Official website
6. LedgerSMB
Best for: Quotations in double-entry accounting
License: GPL-2.0 · Stack: Perl, PostgreSQL · GitHub: 570 stars, repo updated Oct 2026
LedgerSMB supports quotations as part of its order and invoice documents.
Source on GitHub · Official website
Open source vs paid quotation and estimate software
Paid cloud products usually win on polish, mobile apps, automatic bank connections and support. Open source wins on running cost as you grow, data ownership and the freedom to customize. The real cost of open source is hosting, backups, updates and your own time, so count those honestly. Several of these projects also sell hosting or support if you would rather not run a server yourself.
How to choose the best quotation and estimate software
- You want simple quotes and invoices: InvoicePlane or InvoiceShelf.
- Quotes must link to stock and orders: ERPNext or Dolibarr.
- You want a CRM too: See our CRM directory.
Popular tools that are not open source (or not maintained)
These names show up in many "open source" lists, so check the license before you choose them:
- Invoice Ninja: Licensed under the Elastic License 2.0, which is source-available but not open source. Repository
Checked from the projects' LICENSE files and GitHub status on 16 October 2026. Licenses can change.
Mistakes to avoid
A quote can be a binding offer in some countries, so include validity dates and terms. Keep copies of what you sent.
Where to host it
All of these tools can be self-hosted. A small VPS or a web hosting plan from a provider such as Hostinger is enough to get started with most of them. Check each project's requirements first, and read our security and backup checklist before you add real data.
Need a server to host it?
Self-hosting a CRM needs a server. PHP and MySQL apps can often run on ordinary web hosting, while Docker, Node, Python or Java apps usually need a VPS. Check each project's requirements first. Hostinger offers both shared web hosting and VPS plans.
Affiliate disclosure: this is an affiliate link. If you buy through it we may earn a commission at no extra cost to you. CRMs are listed independently of any hosting partner. Learn more.
Related comparisons
- Best Open Source Invoicing Software for Small Business
- Best Open Source Sales Pipeline Software for Small Business
- Best Open Source Accounts Receivable Software (2026)
- Best Open Source ERP Software for Small Business
All open source business software comparisons
- Accounting
- Bookkeeping
- Billing
- Invoicing
- Payroll
- Inventory Management
- Warehouse Management
- Expense Tracking
- Spend Management
- Accounts Payable
- Accounts Receivable
- Cash Flow Management
- Bank Reconciliation
- Purchase Order
- Vendor Management
- Point of Sale (POS)
- Time Tracking
- Quotation & Estimates
- Revenue Recognition
- Financial Reporting
- Asset Management
- Lead Management
- Sales Pipeline
- ERP
Also see our directory of 50 open source CRMs.