EPIC
EPIC Guide
EPIC is TAUS's translation quality estimation and AI post-editing API: it scores every translated segment from 0 to 1 and can automatically fix the segments that fall below your threshold.
EPIC is designed to support, not replace, human decision-making. By identifying where intervention is needed and enhancing quality automatically, it helps to ensure every translation meets your standards.
It assists with quality assessment, error correction, and identifying where human review is needed through:
Our Quality Estimation model, which pinpoints segments that require attention.
Automated Post-Editing, which improves translations in real time.
Together they will help you publish your high-quality content faster, cheaper and in more languages than ever.
TAUS is an independent provider: Quality Estimation and AI Post-Editing are offered as a standalone service, not in combination with machine translation or TMS. The benefit is that you can gain objective, independent quality assessments, ensuring a neutral approach to quality.
In-house data repository: We have a proprietary data repository of 7.4 billion words in almost 500 language pairs, which we use to train our generic and custom QE models. The best customization is achieved when including customer data during model training.
Expert NLP team: With an in-house team of NLP experts we are able to quickly train custom models, enhance the performance of specific language combinations or work on any other requested features.
Translation Quality Estimation (TQE) or Quality Estimation (QE) predicts how good a machine translation is without a human reference translation, giving each segment a score from 0 to 1. It is a vital process in assessing the accuracy and reliability of content, often applied in translation workflows. It uses advanced algorithms to predict the quality of machine-generated content.
A QE model reads the source sentence and its translation and predicts a score for accuracy and fluency; segments below your threshold can be routed to our AI post-editing or for human review. QE flags only the segments needing human or advanced AI attention, allowing businesses to handle large-scale translation projects more efficiently. This streamlines workflows, making them faster and more scalable.
Translation Quality Estimation helps catch potential translation issues early, allowing for quick fixes and a reduction in errors before they impact the final output. It contributes to better resource allocation by identifying segments or areas of content that may require additional attention, optimizing workflows and ensuring that human resources are directed where they are most needed. Ultimately, it enhances the overall reliability and reputation of translation services.
This is done by identifying segments that are likely to require intervention. Instead of reviewing the entire document, translators can focus on specific flagged areas to save time and resources. This benefit is particularly valuable in scenarios where time is of the essence, enabling quicker delivery of high-quality translations to clients.
Read how others achieved this.
QE helps benchmark Machine Translation (MT) engines by evaluating their performance and comparing results. This allows organizations to make data-driven decisions on the best engine for specific projects. By identifying strengths and weaknesses, QE ensures the chosen MT engine meets the accuracy and reliability needs of each project.
Human effort is only used where needed, which significantly decreases the time and cost spent on translation. Massive volumes of machine-translated content can be scored automatically on a quality scale.
After a short learning curve and developing confidence in the models, the adopters of this technology can quickly save 50% of cost and time by locking all segments with quality scores over a certain threshold from human post-editing.
MISCONCEPTION 1
QE will replace humans.
REALITY
QE models highlight critical issues but DO NOT replace human reviewers. They help experts focus on complex errors requiring human judgment, enabling businesses to process 10-100× more content while maintaining quality.
MISCONCEPTION 2
QE is not as accurate as humans
REALITY
Inaccuracy typically stems from poor training data, application outside intended domains, or failure to incorporate human validation loops - not inherent limitations of QE technology itself.
Download our free data-backed QE report to discover how QE actually enhances human expertise by enabling 10-100× faster content processing while maintaining quality standards.
AI post-editing or Automated Post-Editing (APE) is the task of automatically identifying and correcting recurring errors in machine translation (MT) output to improve its quality. Read more.
If an initial translation falls below the required quality score, APE automatically corrects the segment before it reaches the end user.
The step-by-step process is as follows:
TAUS QE model scores the original translation
You can indicate the threshold (0-1) to determine which segments get auto post-edited
TAUS prompts an LLM and returns the translation suggestion.
TAUS carefully validates the steps involved in the APE process. We continuously test various prompting techniques and benchmark the commercially available LLMs for accuracy, latency and cost to ensure the optimal output quality.
However, it is important to note that LLM output quality cannot be guaranteed and it is recommended to run controlled pilots before using APE in a production environment.
Once post-edited, TAUS QE evaluates the output a second time. The revised translation is only accepted if it beats the original score and meets your "fit for purpose" target. If the score doesn't improve or falls short of your defined threshold, the automated system steps back and follows your intended fallback rules—sending the text to a human editor.
Thanks to the prompting technique used to generate the suggested translation, hallucinations are highly unlikely.
We recommend running controlled pilots to assess the accuracy of APE output in their particular domain and language pair.
Yes, APE can be used immediately without additional customization.You can easily test it using the EPIC App by uploading your source files alongside your machine translation (MT) target outputs. To test domain-specific accuracy, you can also upload your own RAG resources (such as glossaries and translation memories). By default, the app runs on our generic model, which is optimized for high performance from English into Spanish, German, Italian, and French (EN ES, DE, IT, FR).
Note: We always encourage running a small-scale sample test first to verify how the default parameters perform for your specific use case.
We offer two kinds of metrics through TAUS EPIC, namely: TAUS QE Scores and custom scores. The latter is only available for custom models and can include any type of label or scoring system. The TAUS QE score is a score from 0-1, with anything closer to 1 being good.
Scoring accuracy of our generic models is tested and validated before release. See the resulting score confidence index per model. We also take user feedback into account and where necessary models are further fine-tuned accordingly.
Specialized and custom models are developed together with a customer and scoring accuracy is validated based on the customer feedback.
More info on QE scoring can be found here.
The quality standard and expectations are subjective and differ per language, domain and content type. It is really up to you and your use case and quality expectations to decide where to draw the line of good and bad quality. However, here are some general recommendations from the TAUS NLP team to interpret the scores and make decisions when using V3 of the generic model:
Above 0.9 — good translations
0.88-0.9 — a gray area (can be good, might have issues)
Below 0.88 — usually indicates at least minor errors
Below 0.8 — serious errors
Below 0.7 — very poor quality
Every language, content type and use case has different quality expectations, and finding the right QE score threshold requires some experimentation. Begin by running small batches of content through the TAUS EPIC API. Use these results to test different thresholds:
Start with higher thresholds (0.9 or 0.95) to ensure only high-quality translations pass through.
Gradually lower the threshold while having human reviewers evaluate both passing and failing segments.
Iterate and fine-tune your workflows based on the results to make sure the threshold reflects your quality standards.
Read more on finding the perfect threshold for your content.
Factors that influence QE scores are:
Accuracy in translation, including proper names, numbers, and specific details.
Over- and undertranslation, in balance to the segment length.
Additions, omissions, word swaps in translations whenever it changes the meaning or makes sentences syntactically incorrect, while still accounting for natural differences in word order between languages.
Punctuation between source and target, with some flexibility for language-specific rules.
Overly formal or informal styles compared to the source text.
Quality Estimation scores should not be confused with the scores generated by Translation Memory software. Full and fuzzy matches do not exist within the context of Quality Estimation, simply because there are no reference translations. Scores are generated based on models that are trained to rate both the accuracy and the fluency of the translations. A perfect translation (or 100% match) therefore does not occur with a QE model.
Quality Estimation models can be somewhat stricter with regard to translation accuracy. If for instance a human translator or post-editor chooses (for stylistic reasons) to skip a word in the translation or use a collective noun (instead of the specific noun), EPIC will return a lower score. A change in the syntaxis of a sentence is usually also penalized by EPIC.
EPIC works inside memoQ, Crowdin, Phrase, Trados, Custom.MT and Blackbird, or through its API. The EPIC API, just like other API-based services, is designed for easy integration into other applications. TAUS offers developer support and resources to assist with integration, further simplifying the process. We also have integrations with memoQ, Crowdin, Phrase, Trados, CustomMT and Blackbird.
EPIC offers real-time and batch endpoints for both quality estimation and automated post-editing. All technical details for users of the TAUS QE models can be found on https://developer.taus.net/
Testing EPIC is simple through our Free Trial.
You can either explore the API's capabilities, assess its performance, and understand how it can enhance your translation quality assessment process, or you can test out the EPIC app.
EPIC offers two ways to process your content: Real-time and Batch.
Both support the same operations for Quality Estimation (QE) and Automatic Post-Editing (APE), but they’re designed for different use cases.
This guide will help you decide when it’s best to use both.
Here you can find the full documentation on the Batch API.
Generic QE Models: A QE model with broad coverage and low specificity, trained on diverse multilingual data to perform well across general content types. This is the default model used for the EPIC free trial and standard plans.
Specialized QE Models: A QE model with moderate specificity, fine-tuned for particular domains or language varieties to improve accuracy where generic models fall short. TAUS develops and distributes this kind of model together with a partner providing the necessary training data, under a partnership agreement granting shared revenues. We currently have the EN -> CA Fr specialized model.
Custom QE Models: A QE model with high specificity, trained with customer-provided data to reflect unique terminology, tone, and style preferences. TAUS develops a custom model for any interested party providing the necessary training data. The custom model is owned by the party requesting it.
Contact us for more information on specialized or custom models.
To train a custom model, we need reviewed and approved translations for at least one language pair and one domain (e.g. a specific customer or product line with consistent style and terminology). Ideally, these include both the original MT output and the final post-edited versions to show how translations are corrected.
We also welcome glossaries or term lists (if they’ve been consistently followed in the data) and a short description of your translation workflow (MT usage, post-editing, review process, and any guidelines used).
RECOMMENDED MINIMUM
A minimum of 25,000 segments is recommended, but more (up to hundreds or thousands) is of course always better.
ACCEPTED FORMATS
We accept TMX, XLIFF, CSV, or other structured formats.
To properly assess the performance of your customized QE model, follow these steps:
1. Create a Gold Standard Test Set
Select at least 500 real-world translation segments from your target domain and language pair. Make sure the test set includes a diverse mix of segments, from accurate translations to those with clear errors. Each segment should be manually labeled with a quantifiable human quality score, such as a scale from 0 to 5, where 5 indicates a perfect translation and 0 indicates a completely unusable one. These human labels serve as the reference (gold standard) for evaluating the QE models.
2. Score the Test Set with Both (Generic and Customized) QE Models
Run the test set through both:
The Generic QE model (as a baseline)
Your Customized QE model
The goal is to highlight where the custom model improves scoring accuracy for your specific content.
3. Compare with Human Judgments
Evaluate how well each model's scores align with the human-assigned labels. Use standard correlation metrics like Pearson or Spearman to quantify this alignment. A higher correlation indicates that the model is accurately reflecting human expectations of quality.
4. Review Disagreements
Identify segments where the model score differs significantly from the human label. Have a human reviewer reassess these cases to:
Correct possible labeling inconsistencies
Understand limitations or blind spots in the model
This helps refine the model and builds confidence in its reliability. By following this process, you ensure that model evaluation is:
Grounded in real data
Repeatable across updates
Validated by human insight where needed
TAUS NLP team carefully checks and benchmarks any update on the QE models. The procedures for benchmarking are described in the 'TAUS Quality Estimation Benchmarking Report', available for download here.
The TAUS data repository contains 7.4 billion words in 483 language pairs and is used to train the generic and custom QE models. For the customization process we also recommend client’s data that can be securely shared with the TAUS NLP team and which is discarded right after the model is trained.
TAUS QE does not store any data that is being sent through the API. Metadata such as language combinations and the quality scores, are stored so that users can gain insights into their quality levels over time, per language pair, per model, etc. through the Reports section of their TAUS account.
TAUS APE uses the LLMs provided by OpenAI and Anthropic. The source and target segments are submitted to the LLMs to generate the auto-post-edited version. TAUS doesn’t store the source and target data submitted for Automated Post-Editing. However, the LLMs used for APE may store the data on their servers for a limited time.
We have a full legal framework in place that can be found here.
Every team is different
Book a tailored EPIC Workshop and learn how your team can work smarter with QE and APE.
See how global enterprises and language service providers are transforming their translation workflows with TAUS. Our success stories highlight real-world results: faster turnaround times, reduced costs, and improved translation quality.
BLEND achieved savings of almost $7,000 a week
Uber saved more than $500,000 in the first year of using EPIC
Milengo saved up to 50% on cost and time

Yamagata saved up to 76% in lead time and costs
See how global enterprises and language service providers are transforming their translation workflows with TAUS. Our success stories highlight real-world results: faster turnaround times, reduced costs, and improved translation quality.
BLEND achieved savings of almost $7,000 a week
Uber saved more than $500,000 in the first year of using Estimate API