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Free patent claim proofreader
Paste your full claim set. Deterministic checks for antecedent basis, claim numbering, dependencies, 112(f) triggers, and indefinite terms — every finding cited to the MPEP or CFR — plus excess-claims fees at current USPTO rates.
Runs entirely in your browser. Nothing you enter is uploaded or stored.
Rules and fees verified August 2026. Informational tool — not legal advice.
Runs entirely in your browser. Nothing you enter is uploaded or stored.
Verify it: open your browser’s developer tools (Network tab) while you analyze — no request carries your text.
What is antecedent basis in a patent claim?
Antecedent basis is the requirement that every definite reference in a patent claim — “the lever”, “said lever” — point back to an element already introduced with an indefinite article (“a lever”) in that claim or in a claim it depends from. A definite reference with no earlier introduction has insufficient antecedent basis, and the claim can be rejected as indefinite under 35 U.S.C. 112(b) (MPEP § 2173.05(e)).
This checker parses the whole claim set, walks each claim’s dependency chain, and tracks introduced phrases against “the X”/“said X” references — including plural/singular mismatches and duplicate introductions that make a later reference ambiguous.
What the proofreader checks
| Check | What it flags | Severity | Authority |
|---|---|---|---|
| Antecedent basis | "the X" / "said X" with no introduction in the claim or its dependency chain; plural/singular mismatches; duplicate introductions | Error / Warning | MPEP § 2173.05(e) |
| Claim numbering | Gaps, duplicate numbers, non-consecutive or out-of-order numbering | Error / Warning | 37 CFR 1.75; MPEP § 608.01(n) |
| Dependencies | References to nonexistent, later, or self claims; multiple dependent claims not phrased in the alternative; an MDC depending from another MDC | Error | 37 CFR 1.75(c) |
| Means-plus-function | "means for" / "step for" limitations that presumptively invoke 112(f) | Note | 35 U.S.C. 112(f); MPEP § 2181 |
| Relative & exemplary terms | "substantially", "about [number]", "generally", "such as", "for example", and similar review candidates | Warning | MPEP § 2173.05(b) |
| Single-sentence rule | Claims containing more than one sentence, or missing the terminal period | Error / Warning | MPEP § 608.01(m) |
| Excess-claims fees | Independent claims over 3, total claims over 20 (MDCs counted per 1.75(c)), and the multiple-dependent-claim fee | Estimate | 37 CFR 1.16; USPTO Fee Schedule |
Findings are labeled review candidates: severity reflects the checker’s confidence, and every finding links to its authority so you can resolve it against the primary source.
USPTO excess-claims fees
Fee amounts below are the excess-claims fees under 37 CFR 1.16(h)–(j), effective January 19, 2025, verified against the USPTO fee schedule in August 2026.
| Fee | Rule | Large | Small | Micro |
|---|---|---|---|---|
| Each independent claim in excess of three | 37 CFR 1.16(h) | $600 | $240 | $120 |
| Each claim in excess of twenty | 37 CFR 1.16(i) | $200 | $80 | $40 |
| Application containing a multiple dependent claim (per application) | 37 CFR 1.16(j) | $925 | $370 | $185 |
For fee counting, a multiple dependent claim is considered to be the number of claims to which it refers — and a claim depending from a multiple dependent claim counts the same way (37 CFR 1.75(c)). The calculator above applies both rules.
Honest limitations
This is disciplined string and phrase tracking — the same class of deterministic checks desktop proofreaders run — not language understanding, and not a legal opinion. It does not check specification support, whether a dependent claim actually further limits its parent (35 U.S.C. 112(d)), claim construction, or anything substantive about patentability. Unusual drafting can produce false positives and false negatives, which is why findings are labeled review candidates and carry their citations.
Formal defects are the cheap part of prosecution. The expensive part is the substance — mapping the examiner’s rejections against the actual references and drafting a grounded response. That is what Sparlo’s full analysis does, on the public record, with every assertion cited.
Frequently asked questions
What does "insufficient antecedent basis" mean in an Office Action?
It means a claim uses a definite reference — "the lever" or "said lever" — for an element that was never introduced with "a"/"an" in that claim or a claim it depends from. Examiners raise it as an indefiniteness issue under 35 U.S.C. 112(b), per MPEP 2173.05(e). The fix is usually mechanical: introduce the element first ("a lever") or conform the reference to the phrase that was actually introduced.
Is there a free alternative to ClaimMaster or PatentOptimizer?
For the deterministic proofreading passes — antecedent basis, dependencies, numbering, 112(f) flags, relative-term checks, and excess-claims fee math — this tool runs them free in your browser with no account. Paid tools do more: ClaimMaster and PatentOptimizer add Word integration, specification-support and part-number cross-checking, amendment and status-identifier review, and figure consistency checks. If you need those, they are worth paying for; if you need a fast claim-set check, this covers it.
Does this replace attorney review?
No. It is a deterministic checker for formal defects, and its findings are review candidates, not legal conclusions. Substantive questions — whether a dependent claim further limits, written-description support, claim construction, patentability — need a qualified practitioner.
Is my claim text uploaded anywhere?
No. The analysis runs entirely in your browser: no network request carries your text and nothing is stored. You can verify this yourself in your browser’s developer tools (Network tab) while running an analysis.
How are excess claim fees calculated?
Under 37 CFR 1.16 you pay for each independent claim over three ($600 large / $240 small / $120 micro entity), for each claim over twenty ($200 / $80 / $40), and a one-time fee if any multiple dependent claim is present ($925 / $370 / $185). A multiple dependent claim counts as the number of claims it references, so one MDC can quietly push a set over the 20-claim line. Rates are from the schedule effective January 19, 2025, verified August 2026.
What is a multiple dependent claim, and why does it cost $925?
A multiple dependent claim refers to more than one preceding claim in the alternative — "The assembly of claim 1 or 2." Filing any MDC triggers the 37 CFR 1.16(j) fee ($925 large entity), and for excess-claims counting the MDC counts as the number of claims it references. It must refer to claims in the alternative only, and it cannot depend from another multiple dependent claim (37 CFR 1.75(c)).
Are words like "substantially" or "about" always indefinite?
No. MPEP 2173.05(b) treats terms of degree as acceptable when the specification provides a standard for measuring the degree — "substantially" appears in a large share of issued claims. The tool flags them as review candidates because they are frequent 112(b) rejection targets, not because they are always wrong.
Why did the checker miss — or over-flag — something in my claims?
It uses disciplined phrase tracking, not language understanding. Unusual drafting, compound references, and chemical or biotech nomenclature can produce both false positives and false negatives. Every finding carries its MPEP or CFR citation so you can resolve it quickly, and severity reflects the checker’s confidence.
Sources
- 01
MPEP § 2173.05(e) — antecedent basis; § 2173.05(b), (d) — relative terms and exemplary language.
https://www.uspto.gov/web/offices/pac/mpep/s2173.html - 02
MPEP § 608.01(m) — single-sentence form of claims; § 608.01(n) — dependent and multiple dependent claims.
https://www.uspto.gov/web/offices/pac/mpep/s608.html - 03
37 CFR 1.75 — claim numbering, dependent claim form, and multiple dependent claim rules.
https://www.ecfr.gov/current/title-37/section-1.75 - 04
37 CFR 1.16 — filing, search, examination, and excess-claims fees.
https://www.ecfr.gov/current/title-37/section-1.16 - 05
USPTO Fee Schedule — current fee amounts (effective January 19, 2025; verified August 2026).
https://www.uspto.gov/learning-and-resources/fees-and-payment/uspto-fee-schedule - 06
MPEP § 2181 — means-plus-function claim limitations under 35 U.S.C. 112(f).
https://www.uspto.gov/web/offices/pac/mpep/s2181.html
The trial is self-serve — no demo call — and runs entirely on public documents.