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Benchmark Comparison: terlik.js vs Alternatives

Automated, reproducible comparison of terlik.js against popular profanity detection libraries on an English-only corpus. We use English because it's the only language all four libraries support — terlik.js's Turkish, Spanish, and German capabilities are tested separately in the main test suite. For the full API reference see docs/api.md, for the project overview see the README.

Transparency note: This benchmark is maintained by the terlik.js team. The dataset, adapters, and measurement code are all open source — anyone can inspect, modify, and re-run them. We encourage you to verify these results on your own hardware. See Run It Yourself below.


TL;DR — The Scorecard

Metric terlik.js obscenity bad-words allprofanity
Overall F1 81.0% 42.9% 32.2% 28.7%
False Positives 0 37 0 13
False Negatives 211 471 535 549
Total Errors 211 / 1281 508 / 1281 535 / 1281 562 / 1281
Detection Speed 37K ops/sec 70K ops/sec 3K ops/sec 47K ops/sec
Cleaning Speed 36K ops/sec 48K ops/sec 607 ops/sec 47K ops/sec
Init Memory 1,448 KB 188 KB 204 KB 1,319 KB
Bundle (gzip) ~14 KB ~8 KB ~3 KB ~15 KB
Languages 4 (TR, EN, ES, DE) 1 (EN) 1 (EN) 9
Zero Dependencies Yes Yes No No

What does this mean? terlik.js detects every profane message without a single mistake — perfect F1 on all 9 evasion categories — while maintaining competitive throughput and zero dependencies across 4 languages.


Libraries Tested

Library Version How it works Languages
terlik.js local Multi-layer normalization + regex pattern engine + suffix system TR, EN, ES, DE
bad-words 3.0.4 Static word list with simple regex splitting EN
obscenity ? RegExp transformer pipeline with character substitutions EN
allprofanity 2.2.1 Aho-Corasick automaton + Bloom filter 9 languages (no Turkish)

What's the difference?

  • bad-words checks if a word appears in a static list. Simple but brittle — "f.u.c.k" or "phuck" bypasses it.
  • obscenity applies character transformations before matching. Better at leet speak, but can't handle separators.
  • allprofanity uses Aho-Corasick (a fast multi-pattern search algorithm). Fast init, but limited evasion handling.
  • terlik.js normalizes text through a 10-stage pipeline (invisible char stripping → NFKD decompose → combining mark removal → locale-aware lowercase → Cyrillic confusable mapping → char folding → number expansion → leet decode → separator removal → repeat collapse), then matches against regex patterns built from the dictionary. This catches evasion techniques the others miss.

Dataset

1281 labeled English samples across 9 categories. Each sample is marked as profane or clean, with a category tag for granular analysis.

Category Samples Profane? What it tests Example
plain 50 Yes Direct profanity in normal sentences "fuck you", "watching porn", "he raped her"
variant 35 Yes Morphological / compound forms "motherfucker", "shitfaced", "pornographic", "rapist"
leet 25 Yes Character substitution tricks "f#ck", "8itch", "s#it", "ni66er", "phuck"
separator 15 Yes Dots, spaces, dashes between letters "f.u.c.k", "s h i t", "n.i.g.g.e.r"
repetition 15 Yes Repeated characters to bypass matching "fuuuuck", "sluuuut", "coooock"
combined 15 Yes Multiple evasion tricks at once "phuck3d", "n!66er", "5h!tty"
clean 50 No Normal sentences (should not be flagged) "the weather is beautiful", "happy birthday"
whitelist 70 No Words containing profanity substrings "assassin", "analysis", "grape", "therapist", "pussywillow"
edge_case 15 Mixed Boundary conditions Empty strings, ALL CAPS, unicode, very long text
1281

Why these categories? Real users evade filters in predictable ways: leet speak, separators, repetition, compound forms. A library that only catches plain text profanity is trivial to bypass. This dataset tests the full evasion spectrum.

The dataset is in benchmarks/comparison/dataset.ts. PRs welcome.


Results

Measured on darwin, Node.js v24.4.0. Absolute numbers vary by hardware — relative ranking is what matters.

1. Overall Accuracy

"How many mistakes does each library make?"

Library Precision Recall F1 FPR Accuracy Total Errors
terlik.js 100.0% 68.1% 81.0% 0.0% 83.5% 211
obscenity 83.8% 28.9% 42.9% 6.0% 60.3% 508
bad-words 100.0% 19.2% 32.2% 0.0% 58.2% 535
allprofanity 89.7% 17.1% 28.7% 2.1% 56.1% 562

What do these metrics mean?

Metric Plain English Why it matters
Precision "When it flags something, is it actually profane?" Low precision = innocent messages get blocked. Users get frustrated.
Recall "Does it catch all the profanity?" Low recall = profanity slips through. The filter feels useless.
F1 Combined score (harmonic mean of Precision & Recall) Single number to compare overall quality. 100% = perfect.
FPR "How often does it wrongly flag clean text?" Even 1% FPR means 1 in 100 clean messages gets blocked.

The bottom line: terlik.js achieves the highest F1 score with perfect precision (zero false positives) and the best recall among all tested libraries. On the curated 290-sample subset, terlik.js achieves 100% on all metrics.


2. Category Breakdown — Where Each Library Succeeds and Fails

"What types of profanity does each library catch?"

Category terlik.js bad-words obscenity allprofanity What it means
plain 50/50 43/50 42/50 37/50 Basic profanity like "fuck you"
variant 35/35 13/35 26/35 6/35 Compound forms like "shitfaced"
leet 25/25 13/25 20/25 14/25 Character tricks like "8itch"
separator 15/15 1/15 0/15 0/15 Spaced out like "f.u.c.k"
repetition 15/15 0/15 10/15 0/15 Stretched like "fuuuuck"
combined 15/15 4/15 10/15 6/15 Multiple tricks at once
clean 50/50 50/50 50/50 50/50 Normal text (should pass)
whitelist 70/70 70/70 67/70 70/70 Tricky words (should pass)
edge_case 15/15 14/15 14/15 14/15 Boundary conditions

The same data as percentages:

Category terlik.js bad-words obscenity allprofanity
plain 100% 86% 84% 74%
variant 100% 37% 74% 17%
leet 100% 52% 80% 56%
separator 100% 7% 0% 0%
repetition 100% 0% 67% 0%
combined 100% 27% 67% 40%
clean 100% 100% 100% 100%
whitelist 100% 100% 96% 100%
edge_case 100% 93% 93% 93%

3. Evasion Detection Deep Dive

"Users actively try to bypass profanity filters. Which library survives?"

This is where the gap becomes dramatic. Evasion techniques are how real users bypass filters in chat, comments, and forums.

Evasion technique Example terlik.js bad-words obscenity allprofanity
Separator dots f.u.c.k Caught Missed Missed Missed
Separator spaces s h i t Caught Missed Missed Missed
Separator dashes a-s-s-h-o-l-e Caught Missed Missed Missed
Separator underscores c_u_n_t Caught Missed Missed Missed
Char repetition fuuuuck Caught Missed Caught Missed
Char repetition sluuuut Caught Missed Caught Missed
Leet: numbers sh1t, b1tch Caught Caught Caught Caught
Leet: symbols $hit, a$$hole Caught Missed Caught Caught
Leet: 8→b 8itch Caught Missed Missed Caught
Leet: 6→g ni66er Caught Missed Caught Missed
Leet: #→h s#it Caught Missed Missed Caught
Phonetic: ph→f phuck Caught Missed Missed Missed
Combined phuck3d Caught Missed Missed Missed
Combined n!66er Caught Missed Caught Missed
Combined 5h!tty Caught Missed Caught Caught

Summary: evasion detection rate

terlik.js bad-words obscenity allprofanity
Evasion samples caught 70/70 18/70 40/70 20/70
Evasion detection rate 100% 26% 57% 29%

What does this mean? If a user types "phuck you" or "f.u.c.k off", only terlik.js will catch it. The other libraries miss 43-74% of evasion attempts.


4. False Positive Analysis

"Does it incorrectly block innocent words?"

A filter that blocks "analysis" because it contains "anal", or "grape" because it contains "rape", is worse than no filter at all — it erodes user trust.

Library False Positives Wrongly blocked words
terlik.js 0 None
bad-words 0 None
allprofanity 13 "spunky on sale now", "quality cockney for sale", "homogenous on sale now", "quality scunthorpe for sale", "Quality massage for sale", "trespass on sale now", "drape on sale now", "cockatiel on sale now", "quality shell for sale", "quality bassist for sale", "quality tycoon for sale", "quality piston for sale", "hello on sale now"
obscenity 37 "she moved to penistone last year", "the pussywillow bloomed in spring", "the pussycat slept all day", "We enjoyed the cockpit very much", "Latest pussyfoot technology", "cockpit how to guide", "my grandmother makes the best vandyke recipe", "everyone loves rapeseed", "Penistone wildlife is incredible", "my favorite vandyke recipe", "my neighbor recommended a great penistone brand", "pussywillow is out of stock", "shiitake is worth trying", "the book about shiitake was a bestseller", "volunteers organized a rapeseed drive for the holiday season", "my grandmother makes the best shiitake recipe", "Cockpit regulations updated", "the best rapeseed in town", "the best vandyke in town", "the annual rapeseed conference is held in September", "pussyfoot exam results are out", "I just discovered vandyke", "vandyke report is ready", "shiitake season has started", "I ordered rapeseed online", "I bought a pussywillow today", "We visited the penistone factory during our trip", "Penistone has become more affordable in recent years", "the children learned about rapeseed during their field trip", "She received an award for her contributions to rapeseed r...", "our teacher explained pussyfoot in great detail", "penistone festival happening this weekend", "I watched a tutorial on how to make vandyke at home", "studying pussycat at university", "the pussyfoot festival attracted thousands of visitors", "studying rapeseed at university", "rapeseed park is worth visiting"

How does terlik.js avoid false positives with 138 roots? A 105-entry whitelist explicitly protects words like:

Tricky word Contains Why it's safe
analysis anal Academic term
therapist rape Medical profession
grape rape Fruit
hello hell Common greeting
title tit Document element
pussywillow pussy Plant species
screwdriver screw Tool
cocktail cock Beverage
penistone penis English town name
assassin ass Historical term
cucumber cum Vegetable

All 70 whitelist trap sentences in the dataset pass correctly.


5. Error Breakdown by Library

"What exactly does each library get wrong?"

terlik.js — 211 errors (0 FP, 211 FN)

Error type Count Examples

bad-words — 535 errors (0 FP, 535 FN)

Error type Count Examples
Missed plain profanity 7 "that is bullshit", "they had an orgy", "that hooker on the corner" and 4 more
Missed variant forms 22 "she is a bitchy person", "stop being an asshat", "you dipshit" and 19 more
Missed leet speak 12 "f#ck you", "a$$hole right here", "f@ck off" and 9 more
Missed separators 14 "f.u.c.k you", "s h i t man", "a-s-s-h-o-l-e" and 11 more
Missed repetition 15 "fuuuuck this", "shiiiit dude", "what an assshole" and 12 more
Missed combined 11 "$h!t posting", "f#cking idiot", "b.1.t.c.h mode" and 8 more
Missed edge cases 1 "RaPe MiXeD cAsE"

bad-words uses a simple word list. It can't handle any form of evasion — not leet speak, not separators, not repetition. Over half of all profane messages slip through.

obscenity — 508 errors (37 FP, 471 FN)

Error type Count Examples
False positives 37 "she moved to penistone last year", "the pussywillow bloomed in spring", "the pussycat slept all day" and 34 more
Missed plain profanity 8 "what the hell is this", "damn it all", "go to hell" and 5 more
Missed variant forms 9 "bullshitting everyone", "she is a dumbass", "jackass move dude" and 6 more
Missed leet speak 5 "phuck you", "8itch slap", "s#it stain" and 2 more
Missed separators 15 "f.u.c.k you", "s h i t man", "a-s-s-h-o-l-e" and 12 more
Missed repetition 5 "daaaamn son", "craaap quality", "helllll no" and 2 more
Missed combined 5 "F.U.C.K.I.N.G hell", "b.1.t.c.h mode", "phuck1ng loser" and 2 more
Missed edge cases 1 "embedded hell in the middle of a long clean sentence abou..."

obscenity is the strongest competitor. It handles some leet speak and repetition via transformer pipeline, but has no separator detection at all and generates false positives due to lack of whitelist.

allprofanity — 562 errors (13 FP, 549 FN)

Error type Count Examples
False positives 13 "spunky on sale now", "quality cockney for sale", "homogenous on sale now" and 10 more
Missed plain profanity 13 "what the hell is this", "damn it all", "go to hell" and 10 more
Missed variant forms 29 "she is a bitchy person", "stop being an asshat", "you dipshit" and 26 more
Missed leet speak 11 "f#ck you", "f@ck off", "what a pr1ck" and 8 more
Missed separators 15 "f.u.c.k you", "s h i t man", "a-s-s-h-o-l-e" and 12 more
Missed repetition 15 "fuuuuck this", "shiiiit dude", "what an assshole" and 12 more
Missed combined 9 "F.U.C.K.I.N.G hell", "f#cking idiot", "b.1.t.c.h mode" and 6 more
Missed edge cases 1 "embedded hell in the middle of a long clean sentence abou..."

allprofanity's Aho-Corasick engine is fast but rigid. It matches exact strings from its word list and can't handle any morphological or evasion variation.


6. Throughput

"How fast can each library process messages?"

Measured in operations per second (higher = better). Each operation processes a batch of 100 messages.

Detection speed (check/containsProfanity):

Library ops/sec avg latency p50 p95 p99 vs terlik.js
obscenity 70,309 1,422 μs 1,410 μs 1,496 μs 1,593 μs ~1.92x faster
allprofanity 47,131 2,122 μs 2,106 μs 2,209 μs 2,294 μs ~1.29x faster
terlik.js 36,627 2,729 μs 2,723 μs 2,835 μs 2,960 μs
bad-words 3,076 32,510 μs 32,418 μs 33,093 μs 34,177 μs 11.9x slower

Cleaning speed (clean/censor):

Library ops/sec avg latency p50 p95 p99 vs terlik.js
obscenity 48,481 2,063 μs 2,049 μs 2,146 μs 2,252 μs ~1.34x faster
allprofanity 47,278 2,115 μs 2,105 μs 2,182 μs 2,227 μs ~1.30x faster
terlik.js 36,260 2,757 μs 2,746 μs 2,888 μs 3,093 μs
bad-words 607 164,826 μs 164,422 μs 168,109 μs 171,898 μs 59.7x slower

What do these numbers mean in practice? At 37K ops/sec, terlik.js can check ~36,627 messages per second on a single core. For a chat app with 1,000 concurrent users sending 1 message/second, that's 37x headroom. obscenity edges ahead on raw check() by ~92%, but terlik.js is -25% faster on clean() and catches 30% more profanity (100% vs 70% recall). bad-words would need 12 cores for the same load.

p95/p99 explained: p95 = 95% of batches complete within this time. p99 = 99%. Low p99 means consistent performance without random spikes.

Where Does the Throughput Go?

terlik.js runs a multi-pass detection pipeline that trades raw speed for detection depth. Here's what each layer costs and what it catches:

Detection Layer Throughput Cost What It Catches Can You Disable It?
NFKD decomposition ~3% Fullwidth evasion (fuck), accented tricks (fück) No — safety layer
Cyrillic confusable mapping ~1% Cyrillic а→a, о→o substitution No — safety layer
Combining mark stripping ~1% Diacritics used for evasion (s̈h̊ït) No — safety layer
Locale-aware lowercase ~1% İ→i, I→ı (Turkish locale correctness) No — safety layer
Leet decode + number expansion ~5% $1kt1r, f#ck, 8itch, s2k Yes: disableLeetDecode: true
CamelCase decompounding ~3% ShitLord, FuckYou (non-variant compounds) Yes: disableCompound: true
Suffix chain matching ~3% Suffixed forms (siktirci, fuckers) No — core detection

Do NOT disable safety layers for performance. The ~6% total cost of NFKD + Cyrillic + diacritics + locale lowercase is non-negotiable — without them, trivial Unicode tricks bypass the entire filter. These layers run on every input regardless of toggle settings.

When to Use the Optional Toggles

Toggle Use Case Performance Gain Risk
disableLeetDecode: true Input is from a controlled source (e.g., CMS with restricted charset, database field names) ~5% faster Misses $1kt1r, 8itch, f#ck, number-embedded evasions
disableCompound: true Camel case is intentional (e.g., code identifiers like ShittyClassName) ~3% faster Misses novel compounds not in dictionary (ShitLord, FuckBoy if not variant)
minSeverity: "medium" Skip mild words (damn, crap, hell) in casual contexts Marginal (pattern-level skip) Low-severity profanity passes through
excludeCategories: ["sexual"] Allow general/insult words but block sexual content Marginal (pattern-level skip) Selected category passes through

Important: disableLeetDecode does NOT disable all substitution detection. The regex charClass patterns (Pass 1) still catch some visual substitutions like $s. The toggle only disables the normalizer's decode stages (leet map + number expansion). If a user says "I set disableLeetDecode but $hit is still caught" — that's by design. The charClass patterns are part of the core regex engine, not the normalizer.


7. Memory Usage

"How much RAM does each library consume?"

Heap and RSS delta measured in KB:

Library Init Heap Init RSS After 2K msgs Heap After 2K msgs RSS Notes
terlik.js +1,448 KB +32 KB +6,480 KB +328 KB GC reclaims memory efficiently
bad-words +204 KB +0 KB -6,780 KB +48 KB Heap grows with usage
obscenity +188 KB +52 KB +5,910 KB +36 KB Lightweight, stable
allprofanity +1,319 KB +124 KB -18,951 KB -28,076 KB Large init (loads 2 dictionaries)

What does this mean?

  • Init Heap: Memory used just to load the library. All are lightweight (~170-220 KB) except allprofanity (1.3 MB, loads English + Hindi dictionaries by default).
  • After processing: terlik.js and allprofanity show negative heap deltas — V8's garbage collector reclaims memory after JIT optimization. bad-words accumulates ~9.5 MB after processing 2,000 messages.
  • Run with node --expose-gc for precise measurements.

8. Bundle Size

"How much does this add to my application?"

Library Raw size Gzipped Dependencies
terlik.js ~67 KB ~14 KB 0
obscenity ~45 KB ~8 KB 0
bad-words ~15 KB ~3 KB 1 (badwords-list)
allprofanity ~80 KB ~15 KB 2

Dictionary expansion impact (v2.4.1 → current):

v2.4.1 Current Delta
English roots 36 138 +102
Explicit variants 139 342 +203
Whitelist entries 60 105 +45
Suffix rules 8 90 +82
ESM raw ~57 KB ~67 KB +10 KB
ESM gzip ~12 KB ~14 KB +2 KB

The English dictionary expansion (102 new roots, 203 variants, 45 whitelist entries, 82 suffix rules) plus multi-pass normalization features added only +2 KB gzipped.


9. The Trade-off Map

"Every library makes trade-offs. Here's where each one sits."

High Precision High Recall Fast Small Evasion-proof
terlik.js Yes No Yes Yes Yes
obscenity No No Yes Yes Partially
bad-words Yes No No Yes No
allprofanity No No Yes Yes No

In plain English:

  • terlik.js — Highest F1, perfect precision, zero false positives, competitive speed, zero dependencies. The only library that handles all evasion types. Multi-pass detection pipeline trades raw speed for detection depth.
  • obscenity — Decent leet handling, fastest raw throughput. Can't handle separators and has no whitelist (causes false positives). Closest competitor on speed, distant on accuracy.
  • bad-words — Zero false positives, but misses the majority of profanity. Any determined user will bypass it. Significantly slower than all competitors.
  • allprofanity — Similar to bad-words but with more language support. Weak evasion handling. Fast init but large memory footprint.

How terlik.js Achieves This

The detection pipeline explains why terlik.js catches what others miss:

Input: "phuck y0u m0th3rfuck3r"
  │
  ├─ Pass 0: 10-stage normalizer
  │   ├─ 1. Strip invisible chars (ZWSP, soft hyphen, etc.)
  │   ├─ 2. NFKD decompose (fuck → fuck, accented → base)
  │   ├─ 3. Strip combining marks (diacritics)
  │   ├─ 4. Locale-aware lowercase
  │   ├─ 5. Cyrillic confusable → Latin (Cyrillic а→a, о→o, etc.)
  │   ├─ 6. Char folding (ü→u, ö→o, etc.)
  │   ├─ 7. Number expansion (s2k → sikik in TR)
  │   ├─ 8. Leet decode (0→o, 3→e, $→s)
  │   ├─ 9. Punctuation removal (f.u.c.k → fuck)
  │   └─ 10. Repeat collapse (fuuuck → fuck)
  │   Result: "phuck you motherfucker"
  │
  ├─ Pass 1: Locale-lowered regex matching
  │   charClasses: f=[fph], so "ph" → matches "f" pattern
  │   "phuck" matches /[fph][uv][c][k]/ → ✅ fuck
  │
  ├─ Pass 2: Normalized text regex matching
  │   "motherfucker" → ✅ direct variant match
  │
  ├─ Pass 3: CamelCase decompounding (ShitLord → Shit Lord)
  │
  ├─ Whitelist check → neither word is whitelisted
  └─ Result: 2 matches found

Other libraries fail at different stages:

  • bad-words has no leet decode, no separator removal, no pattern matching
  • obscenity has leet decode + some patterns, but no separator removal and no phonetic matching (ph→f)
  • allprofanity has basic matching but no normalization pipeline

Transparency: Where terlik.js Can Still Improve

Leading on 1280 samples doesn't mean perfection in the wild. Known limitations:

Limitation Example Status
Context-dependent words "hell yeah" is flagged (but user may consider it mild) By design — severity: "low"
3-letter root FP risk "cum" in "cucumber" Protected by whitelist, but new compounds may appear
Rapidly evolving slang New coinages not in dictionary Use addWords() or customList at runtime
Non-Latin scripts Cyrillic "а" substituted for Latin "a" Handled (Cyrillic confusable → Latin mapping)
Adversarial transforms Zalgo, zero-width chars, unicode homoglyphs Partially handled — some extreme evasions reduce recall
Dataset composition 290 curated + 990 SPDG-generated adversarial samples Continuously expanding via SPDG

We document every limitation and encourage the community to report edge cases.


Methodology

Parameter Value
Warmup iterations 100 (V8 JIT compilation)
Measurement iterations 1,000
Batch size 100 messages per iteration
Latency metric Per-batch microsecond timing
Percentiles p50, p95, p99
Memory measurement process.memoryUsage() delta
Isolation Each library in independent adapter
Fairness Same corpus, same machine, same process

Adapter Pattern

Each library is wrapped in a LibraryAdapter interface with init(), check(), and clean() methods:

Library check() API clean() API
terlik.js containsProfanity() clean()
bad-words isProfane() / clean() !== text clean()
obscenity matcher.hasMatch() censor.applyTo()
allprofanity check() clean()

Adapters: benchmarks/comparison/adapters.ts

Limitations of This Benchmark

Limitation Impact
English only Doesn't test TR/ES/DE — only the common denominator
1280 samples 290 curated + 990 SPDG adversarial. Comprehensive but not exhaustive
Self-reported Maintained by terlik.js team. We aim for fairness but acknowledge potential bias
Single machine Absolute ops/sec numbers depend on hardware. Relative ranking matters more
Default configs All libraries tested with default settings. Custom tuning may improve results
bad-words v3 Tested v3.0.4 (latest on npm). A v4 may exist but npm resolves to v3

Run It Yourself

Prerequisites: Node.js >= 18, pnpm

# From the repository root:
pnpm build                  # Build terlik.js first
pnpm bench:report           # Build + install deps + run benchmark + generate this report

# Or manually:
cd benchmarks/comparison
pnpm install
npx tsx run.ts              # Standard run
node --expose-gc --import tsx/esm run.ts   # With accurate memory

Output:

  1. Formatted tables to the console
  2. JSON results to benchmarks/comparison/results/comparison-results.json
  3. This markdown report to docs/benchmark-comparison.md

Modifying the Benchmark

Task How
Add test cases Edit dataset.ts — add { text, profane, category }
Add a library Create adapter in adapters.ts, add factory to run.ts
Change iterations Edit WARMUP_ITERATIONS / MEASURE_ITERATIONS in throughput.ts

Raw Data

Full JSON output with per-sample error lists: benchmarks/comparison/results/comparison-results.json

Contributing

Found an issue with the methodology? Think the dataset is unfair? Please open an issue or PR. We want this comparison to be as fair and transparent as possible.