If you are looking for the best invoicing software that supports digital signatures, it is usually because of a job that went sideways. You sent a quote, the client said go ahead on the phone, you did the work, and now they remember a lower price or a smaller scope. You have a PDF and a memory of a conversation. Neither settles it.
The short answer: the best invoicing software for digital signatures is the one that captures the client's signature at the moment they say yes, on the quote, before you start. QuickBooks Online, FreshBooks, Zoho Invoice, Invoice Ninja, Square and HoneyBook can each do this in some form. Xero and Billbooks record a one-click acceptance instead of a signature.
Is this you?
- Clients approve quotes by replying "looks good" to an email, or by phone.
- You have started a job without anything in writing, because waiting felt like losing it.
- A client has disputed a price or a scope after the work was done.
- You print quotes, ask clients to sign and scan them back, and most never do.
- You are not sure whether "signature" in your invoicing app means your signature or the client's.
That last one causes more confusion than any other, so it comes first.
Two different signatures, and which one you need
Your signature on the document. An image of your signature printed on every invoice or quote you send. It makes the document look official and some clients, especially larger ones and public bodies, expect it. It proves nothing about what the client agreed to.
The client's signature on the quote. The client opens the quote, signs it, and the tool stores the signed copy with a date. This is the one that protects you, because it records who agreed to what price and when. It is also called an e-signature, or accepting a quote with a signature.
Most comparison lists mix the two up. When a tool says it supports digital signatures, check which one it means.
Why the yes goes missing
A quote is easy to send and easy to ignore. Clients rarely say no in writing. They go quiet, or they say yes in whatever channel is nearest: a call, a text, a reply in a long email thread. Our own quote data shows how rarely a quote gets a clear answer at all:
Of quotes sent at least six months ago, 45.5% have still never been answered either way (398 of 875 quotes, 30 businesses). Almost no client ever formally declines: that bucket is too small to report under our own 25-business threshold, which is the finding.
Source: Billbooks quote study, 1,125 quotes from 43 small businesses, last 24 months (aggregate only, figures shown only where 25+ businesses and 100+ documents contribute). See the quote study.
A signature step does not make clients answer. What it does is give the yes a single, fixed place to land, attached to the exact version of the quote they saw.
What it costs when the yes is not written down
The cost shows up at the invoice. If the client remembers a different scope, you either argue, discount, or write off the difference. If the job had a deposit, there is no record of what the deposit was a deposit on. And when a quote was revised twice, nobody is sure which version was agreed. None of that is a legal problem most of the time. It is a time and money problem, and it lands on the person who did the work.
Are e-signatures legally valid?
In the US, the federal ESIGN Act says a signature or contract in interstate or foreign commerce may not be denied legal effect solely because it is in electronic form (15 U.S.C. 7001). Other countries have their own rules, and some documents still need a wet signature. For an ordinary quote, a stored e-signature is far stronger evidence than an email that says "sounds good". For a large contract, or if a dispute is already under way, talk to a lawyer. This article is general guidance, not legal advice.
What to check before you choose
1. Can the client sign the quote, or only click accept?
A click records that someone with the link pressed a button. A signature records a name typed or drawn by the person agreeing. Both beat an email. A signature is the stronger record.
2. Is the signature built in, or a separate product?
Some tools sign inside the invoicing app. Others hand the signing to a sister product or a third-party service, which can mean a second account and its own usage limits.
3. Which plan is it on?
Signing is often on a higher tier than invoicing. Check the plan you would actually pay for, not the top one.
4. What happens when you change the quote after it is signed?
A good tool resets the signature when the price or scope changes, so the client signs the version you will actually invoice. Check this on a trial.
Which tools let clients sign
From each company's own help and product pages, read in October 2026 and linked beside each entry. We list only what we checked, so a tool that is not here has not been checked, not ruled out.
- QuickBooks Online has a Require e-signature toggle on estimates. The customer types their full legal name to sign before accepting or paying a deposit, and QuickBooks emails a signed PDF to both sides and stores it on the estimate. It is on Simple Start, Essentials, Plus and Advanced, is for estimates only, not invoices, and allows one signer per estimate. Changing amounts after signing sends the estimate back to pending for a new signature (QuickBooks: require an e-signature on estimates). See Billbooks vs QuickBooks.
- FreshBooks puts the e-signature on proposals. You turn on Require e-signature per proposal, the client clicks Accept and then signs, and a signed proposal can no longer be edited. Proposals are on the Plus and Premium plans (FreshBooks: how do I create a proposal). See Billbooks vs FreshBooks.
- Zoho Invoice does it through Zoho Sign. With the integration connected and Customer Signature for Estimates turned on, a client accepting an estimate in the customer portal is asked to sign first, by drawing, typing or uploading an image. Signatures count toward your Zoho Sign plan usage (Zoho Invoice: integrate with Zoho Sign). See Billbooks vs Zoho Invoice.
- Invoice Ninja signs through DocuNinja, its sister e-signature product, which shares your Invoice Ninja login. Invoices, quotes and purchase orders can be signed in the client portal, and a document set to need a signature blocks payment or quote approval until it is signed. Its guide does not say which plan includes it, so check before you count on it (Invoice Ninja: e-signatures). See Billbooks vs Invoice Ninja.
- Square does it with Square Contracts, a separate document you attach to an invoice or estimate. The customer initials and signs, and gets a PDF copy. On Invoices Plus you can require the contract to be signed before the invoice can be paid (Square: create and send contracts). See Billbooks vs Square Invoices.
- HoneyBook builds signing into its contract smart files. The client types or draws a signature, cannot reach the invoice that follows until they sign a required contract, and editing a signed contract invalidates the signature and asks them to sign again (HoneyBook: how clients interact with contracts). See our HoneyBook alternative guide.
- Bonsai sells contract e-signing as part of the product, sent through Bonsai or your own secure link, with reminders and a notification when the client views and signs (Bonsai: contracts). Its proposals use electronic approval. See Billbooks vs Bonsai.
- Xero lets customers accept or decline a quote online with a single click and leave comments, and emails you when they accept. Its quotes page describes no signature step (Xero: quotes and estimates). See Billbooks vs Xero.
- Billbooks sits with Xero on this one. A client can approve or decline a quote from its link, with no login, the quote's status changes on your side, and with notifications switched on you get an email naming the client and the time. The client does not sign. What Billbooks does have is your own signature and a payment QR code, added once and printed on every invoice, on every plan from $7.95 a month. See digital signatures and QR codes in Billbooks.
So the choice follows the work. If your quotes are routine and the risk is a forgotten yes, a one-click approval with a timestamp may be enough. If you need the client's name on the quote before you buy materials, QuickBooks Online and Zoho Invoice sign the estimate itself. If the agreement is really a contract with terms, HoneyBook, Bonsai and Square treat it as one, and Invoice Ninja covers both.
Put the scope in writing before anyone signs
Most disputes are about what was included, not about the signature. Write the quote with every line, the price, and an expiry date, and download it to send today.
What to do now, with what you already have
- Ask for the yes in writing, every time. Even with no signing tool, reply to a verbal yes with: "Great, please reply to confirm you accept quote number 104 for $2,400." A reply that names the number and the amount is a usable record.
- Put an expiry date on every quote. It gives the client a reason to answer and stops an old price staying open for a year.
- Number your quotes and never edit a sent one. Issue a new number for a revision, so there is never doubt about which version was agreed.
- Take a deposit on bigger jobs. A paid deposit against a numbered quote is strong evidence of agreement on its own.
- Try the signing step as the client. On a trial, send a quote to your own email, open it on your phone, and sign it. If it takes more than a minute, your clients will skip it.
If a client is already disputing a quote
Gather what you have before you reply: the quote they received, the date it was sent, and any message where they said yes. Send one calm message that attaches the quote and quotes their reply back to them, then asks which line they see differently. Keep it to the document, not the memory. If the amount is large and they will not engage, that is the point to get advice from a lawyer or your local small claims guidance rather than argue by email.
How to stop it happening again
The habit is simple: no work starts until the yes is attached to a specific, numbered quote. A signing tool makes that automatic. Without one, a written reply that names the quote does most of the same job. Pick the tool by the four checks above, and by how much a disputed job would cost you.
If you send quotes and then invoice from them, see which software turns a quote into an invoice, and for what clients see when they open your link, invoice software with a client portal.
Free tools to get a clear yes on your next quote
Frequently asked questions
What is the best invoicing software that supports digital signatures?
It depends on what needs signing. QuickBooks Online and Zoho Invoice let a client sign an estimate before accepting it. FreshBooks puts the e-signature on proposals. HoneyBook, Bonsai and Square sign a contract alongside the invoice, and Invoice Ninja signs quotes and invoices through DocuNinja. Xero and Billbooks record a one-click acceptance instead.
How do I add a digital signature to an invoice?
Most invoicing tools let you upload an image of your own signature once in the invoice settings, and it then prints on every invoice. In Billbooks this is in Invoice Settings on every plan. A client signature is different: it is captured when the client accepts a quote or contract, not on the invoice itself.
Can a client sign a quote online?
Yes, in tools with an e-signature step on quotes or estimates. In QuickBooks Online the customer types their full legal name. In Zoho Invoice, with Zoho Sign connected, the client draws, types or uploads a signature when accepting in the customer portal. Other tools record a one-click acceptance without a signature.
Is an e-signature on a quote legally binding?
In the US, the ESIGN Act says a signature or contract may not be denied legal effect solely because it is electronic. Rules differ by country and some documents need a wet signature. For a large contract or an active dispute, ask a lawyer.
What is the difference between a digital signature and an e-signature on an invoice?
In invoicing apps the words are used loosely. Usually digital signature means an image of your own signature printed on the document, and e-signature means the client signing to accept. Strictly, a digital signature is a cryptographic method, which most invoicing tools do not use.
Do I need a signed quote if the client accepts by email?
An email that names the quote number and the amount is a usable record for most small jobs. A signed quote is stronger because it is attached to the exact version the client saw. For larger jobs, take a deposit against the numbered quote as well.
