# Appen vs String Catalog

Appen records 665,840 monthly visits with +0.2% month-over-month growth and Contact for Pricing pricing. String Catalog records 468 monthly visits with -66.7% growth and Paid pricing.

| Metric | [Appen](https://openaitools.app/tool/appen-com) | [String Catalog](https://openaitools.app/tool/string-catalog) |
| :--- | :--- | :--- |
| Website URL | https://appen.com | https://stringcatalog.com |
| Categories | AI Models, Large Language Models (LLMs), AI Developer Tools | AI Translate, AI Developer Tools, AI GitHub, AI Workflow |
| Pricing Model | Contact for Pricing | Paid |
| Monthly Visits | 665,840 | 468 |
| MoM Growth Rate | +0.2% | -66.7% |
| Primary Market | United States | Global |
| Direct Visits | 238,314 | 185 |
| Review Score | 4.4 | 4.3 |
| Saved Count | 2 | 0 |
| Supported Platforms | Website | Website |

## Appen

Appen is one of the oldest pure-play AI data companies, tracing its roots to 1996 when it began building human-labeled datasets for speech recognition and NLP. Over three decades it supported successive generations of model development — search relevance in the 2000s, machine translation, deep-learning vision annotation, Transformer-era semantics, GPT-3 scale corpora, RLHF for conversational AI, and now agentic and multimodal foundation models.

Today Appen positions itself around six specialised capability areas: Frontier Alignment (chain-of-thought reasoning traces, SME RLHF, supervised fine-tuning demonstrations, adversarial red teaming), Agentic AI (golden trajectories, RL environment design, failure-mode taxonomies, SWE-driven evaluation), Multimodal and Speech AI (multilingual ASR and conversational corpora, expressive TTS annotation, VLM training data, video action labelling), Physical AI (LiDAR point-cloud annotation, multi-camera sensor fusion, robotics demonstration trajectories, world-model rollouts), Model Integrity (hallucination benchmarking, bias detection, regulatory audits and continuous monitoring), and Research Services (context engineering, calibrated LLM-as-a-judge, synthetic data and custom benchmarking).

Delivery runs through Appen's AI Data Platform (ADAP), which blends automation with human oversight, and the company cites SOC 2 and ISO 27001 certification, 500+ global locales, and a client roster that includes major cloud, search, retail and aerospace organisations. Appen does not publish self-serve pricing; engagements start with a scoping conversation and are quoted per project, so cost depends on data volume, language coverage, modality and annotation complexity.

**Pricing & Plans:** Enterprise/contact-for-pricing. Appen does not publish self-serve plans; projects are scoped and quoted individually. Appen also sells off-the-shelf (OTS) datasets and crowd/contractor workforce programs with separate terms.

- **Frontier alignment data:** Chain-of-thought reasoning traces, SME-level RLHF, supervised fine-tuning demonstrations and adversarial red teaming for the most capable models.
- **Agentic AI datasets:** Golden trajectories, RL environment design, failure-mode taxonomies and software-engineering-driven deep evaluation for autonomous agents.
- **Multimodal and speech corpora:** Multilingual ASR and conversational speech data, expressive TTS annotation, vision-language model training data, video action labelling and voice-agent evaluation.
- **Physical AI annotation:** LiDAR point-cloud labeling, multi-camera sensor fusion, robot demonstration trajectories, world-model rollouts and embodied interaction logs.
- **Model integrity and evaluation:** Hallucination benchmarking, bias detection, regulatory audits and continuous monitoring, plus independent model evaluation.
- **AI Data Platform (ADAP):** A production platform that combines automation with human oversight, with SOC 2 and ISO 27001 certification and 500+ locales covered.

**Strengths:** Three decades of annotation methodology, tooling and workforce management experience; Very broad coverage: frontier alignment, agentic, speech, multimodal, physical AI and evaluation in one vendor; 500+ locales and multilingual expertise that most in-house teams cannot match; Enterprise-grade security posture (SOC 2, ISO 27001) and publicly listed governance

**Limitations:** No transparent self-serve pricing; every engagement requires a sales/scoping cycle; Enterprise-oriented contracts can be heavy for small teams or indie developers; Quality depends on workforce management, so results vary by project and locale; Overlaps with many cheaper specialist annotation vendors, making vendor selection non-trivial

[Profile (Markdown)](https://openaitools.app/tool/appen-com.md)

## String Catalog

String Catalog keeps localization inside source control instead of spreading it across spreadsheets and side tools. You connect the repository you already ship from, choose the branch you release from, and String Catalog proposes translation updates as clean diffs that your team reviews and merges like any other change. Native formats stay native: .xcstrings files for Apple platforms and Android strings.xml both round-trip without hand cleanup or one-off scripts.

The product deliberately covers more than raw strings. App Store and Google Play release notes and store listing copy can be prepared in the same workspace, with platform-specific field limits, locale codes, and exportable output that growth teams can ship directly. Tone guidance, protected brand terms, and glossaries travel with every new language so the result sounds like your app rather than a generic machine translation.

Quality control is built into the loop. Reviewers get secure no-login links, suggested fixes appear in review queues, and low-confidence output can be retried before release week. Pricing is deliberately flat across languages: every plan covers up to 40 languages, so cost depends on string volume and workflow needs rather than how many markets you enter.

**Pricing & Plans:** Paid subscription with a monthly or annual option (annual saves about 20%) and one free language to trial. Published plans are Hobby at $15/month, Pro at $45/month, and Business at $75/month, differing mainly by base string-key limits and review features. All plans include up to 40 languages and no per-language charge. Check the site's cost calculator for current figures.

- **Git-native, reviewable workflow:** Connect GitHub, GitLab, or Bitbucket and receive localization updates as pull requests and clean diffs on the branch you release from, so your repository stays the single source of truth.
- **Native format support:** Round-trip .xcstrings for Apple platforms and Android strings.xml without spreadsheet export, broken builds, or custom scripts.
- **Release notes and store metadata:** Translate App Store and Google Play release notes and store listing copy in the same product, with platform-specific field limits and locale handling.
- **Brand voice and glossary controls:** Protect brand terms, add tone guidance, and reuse glossaries so each new locale keeps the product voice users already know.
- **Human review with secure links:** Share no-login review links, inspect suggested fixes in review queues, and bulk-accept edits when a translation needs more than an automatic pass.

**Strengths:** Stays inside the Git workflow teams already trust, with pull requests and clean diffs instead of silent content mutation; Flat pricing across up to 40 languages removes per-locale cost math and makes adding markets predictable; Covers strings, release notes, and store metadata in one product instead of three separate tools; Human review tooling, protected terms, and tone guidance are included rather than bolted on

**Limitations:** Built primarily around iOS and Android app workflows, so web or backend-only projects may find it a tight fit; Review quality features such as shared review links and accuracy monitoring are limited to higher-priced Pro and Business plans; Base string-key ceilings on each tier mean very large apps need to size plans carefully or move up a level

[Profile (Markdown)](https://openaitools.app/tool/string-catalog.md)

## Frequently Asked Questions

### How do Appen and String Catalog compare in monthly traffic?

Appen has 665,840 monthly visits, while String Catalog has 468. Traffic estimates describe audience size, not product quality.

### How do their growth rates compare?

Appen has a month-over-month growth rate of +0.2%; String Catalog has -66.7%.

### How does pricing compare?

Appen: Contact for Pricing. Enterprise/contact-for-pricing. Appen does not publish self-serve plans; projects are scoped and quoted individually. Appen also sells off-the-shelf (OTS) datasets and crowd/contractor workforce programs with separate terms. String Catalog: Paid. Paid subscription with a monthly or annual option (annual saves about 20%) and one free language to trial. Published plans are Hobby at $15/month, Pro at $45/month, and Business at $75/month, differing mainly by base string-key limits and review features. All plans include up to 40 languages and no per-language charge. Check the site's cost calculator for current figures.

## Alternatives

| # | Tool Name | Monthly Visits | MoM Growth Rate | Pricing Model | Summary | Profile (Markdown) |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | [Prolific](https://openaitools.app/tool/prolific-com) | 18,697,671 | -1.8% | Paid | Connects teams directly with verified human participants for preference tuning and studies, but lacks managed end-to-end labeling pipelines. | [.md](https://openaitools.app/tool/prolific-com.md) |
| 2 | [Invisible Technologies](https://openaitools.app/tool/invisible-technologies-inc) | 1,364,520 | +64.4% | Contact for Pricing | Blends custom software with dedicated human expert teams to handle complex operations, but operates as a bespoke service. | [.md](https://openaitools.app/tool/invisible-technologies-inc.md) |
| 3 | [Labelbox](https://openaitools.app/tool/labelbox) | 762,803 | -22.8% | Contact for Pricing | Combines robust data labeling tools with automated workflows, but focuses more on software tooling than managed human workforces. | [.md](https://openaitools.app/tool/labelbox.md) |
| 4 | [Phrase](https://openaitools.app/tool/phrase) | 639,121 | -8.7% | Free Trial, Paid, Contact for Pricing | AI-powered localization and translation platform for global content | [.md](https://openaitools.app/tool/phrase.md) |
| 5 | [Scale](https://openaitools.app/tool/scale) | 616,915 | +12.5% | Contact for Pricing | Provides enterprise-grade AI training data and model evaluation at massive scale, but often with higher enterprise pricing. | [.md](https://openaitools.app/tool/scale.md) |
| 6 | [SuperAnnotate](https://openaitools.app/tool/super-annotate) | 386,034 | +37.4% | Free Trial, Contact for Pricing | Delivers advanced multimodal data curation and annotation infrastructure, but requires your own annotation workforce for labeling tasks. | [.md](https://openaitools.app/tool/super-annotate.md) |
| 7 | [Arize AI](https://openaitools.app/tool/arize-com) | 249,028 | +3.2% | Paid, Contact for Pricing | Agent observability, evaluation, and continuous improvement for production AI | [.md](https://openaitools.app/tool/arize-com.md) |
| 8 | [Encord](https://openaitools.app/tool/encord-com) | 244,204 | +9.4% | Contact for Pricing | The multimodal data layer for computer vision and physical AI teams | [.md](https://openaitools.app/tool/encord-com.md) |
| 9 | [Localazy](https://openaitools.app/tool/localazy) | 164,291 | -14.8% | Freemium, Free Trial, Paid | Software localization on autopilot with AI drafts and human review | [.md](https://openaitools.app/tool/localazy.md) |
| 10 | [Defined.ai](https://openaitools.app/tool/definedcrowd-com) | 146,251 | -21% | Contact for Pricing | Offers pre-packaged AI training datasets and custom data collection services, but with a smaller global crowd than Appen. | [.md](https://openaitools.app/tool/definedcrowd-com.md) |

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Source: https://openaitools.app/compare/appen-com-vs-string-catalog

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