Microtask crowd · Multilingual language data
Sigma AI
Sigma AI specializes in multilingual language data at scale (700+ languages, founded in Madrid in 2008), running discrete per-language projects with named linguist-expert tiers. Its careers portal exposes a live JSON feed.
Third-party reports
Is Sigma AI legit?
Researched Nov 2026 · 14 sourcesMostly. Sigma AI is a real Madrid data company, founded in 2008 with offices in London and Miami, but it publishes no freelance rates or payment terms, and its few public worker reviews are mostly negative. Its job posts state no pay, applicants report unpaid tests that go unanswered, and workers describe per-minute transcription pay and one-sided contract terms, so ask for the rate and read the contract before you invest time. It pays Not stated; Madrid transcribers report ~€7–€9/hr (Glassdoor) (third-party reports).
Listed in our live directory
Daniel Tapias (CEO) and Nuria Gómez Bermejo (CFO) founded Sigma in Madrid in 2008; it also has offices in London and Miami. It collects and annotates speech, text, image and video data for AI, now also sells AI evaluation, and shows Google, Microsoft, AWS and Samsung among its clients. Read on 5 November 2026, its own pages differ on size (2,500+ to 70,000+ people, 200+ to 700+ languages), and 86 of its 88 job posts claim over 30 years of experience.
Remote linguists work as freelancers under a commercial contract. None of the 88 posts on its careers feed on 5 November 2026 states a rate, and Sigma publishes no payment schedule or method. Reviewers describe low pay per minute of transcribed audio; one says payments are regular, while others report unpaid work.
Trustpilot 2.6/5 (7 reviews) · Trustpilot (sigma-ai.com) 2.2/5 (8 reviews). Read November 2026.
Language-driven: each posting asks for fluent or native speakers of a named language, a few for a pair or trio (Czech and English, Korean and Japanese; German, Russian and English). Of its 88 postings on 5 Nov 2026, 72 are tagged Fully Remote, 15 are on-site in London and 1 in Madrid (careers.sigma.ai/jobs.json). Its postings describe offices in Spain, the US and the UK.
No Sigma-specific impersonation cases turned up in a web search on 5 November 2026. Real openings are listed at careers.sigma.ai, and Sigma's job posts say it never hires through agents or other third parties. Other companies share the Sigma name, so check the domain is sigma.ai. Never pay to get work; fake recruiters often start on text, WhatsApp or Telegram.
What people praise
- One reviewer, posting in September 2025 and again in January 2026, praises supportive managers and regular payments.
- Work is remote on a platform open around the clock, and many projects ask only for fluency in the languages and basic computer skills.
What people complain about
- Applicants say they transcribed test audio (one says five files) and then heard nothing back, or got no answer to questions about a confusing test.
- A June 2026 reviewer says his wife, paid per minute of transcribed audio, sat unpaid meetings, lost work to crashes and had not been paid for about 80 hours over two weeks.
- A second Trustpilot profile, for sigma-ai.com (which redirects to sigma.ai), has 8 reviews, all 1-star, reporting pay of $2 to $3 an hour, a recording project cut short after 75 files and work never paid.
- A December 2025 reviewer says the contract came through Sigma's US office with one-sided clauses, and urges legal advice before signing. Sigma has not replied to any review.
Best for: Native or fluent speakers of the languages Sigma recruits for (many Indian, Asian and European languages) who want occasional remote transcription, annotation or recording work. Not for: Anyone who wants to know the rate before spending hours on tests, needs predictable income, or is not ready to read a freelance contract closely.
Honest catches
- Pay here is third-party reports, not measured live from a job feed, so treat it as a benchmark rather than a guaranteed rate.
Sources for this review
- Sigma AI: About (founders, headquarters, 25K+ annotators, 500+ languages; read November 5, 2026)
- Sigma AI: FAQs (founded 2008 in Madrid, offices, 500+ languages; read November 5, 2026)
- Sigma AI: homepage (18+ years, 70K+ experts, 700+ languages, clients, AI data and evaluation; read November 5, 2026)
- Sigma AI Careers (Madrid, London and Miami, more than 2,500 people; read November 5, 2026)
- Sigma AI Careers: job feed (88 posts, read November 5, 2026)
- Sigma AI Careers: Cantonese Chinese (Traditional script) Linguistic Projects (Remote), posted October 19, 2026
- Sigma AI Careers: Swedish Linguistic Projects (On-site London), posted October 27, 2026 (200+ languages)
- Trustpilot: sigma.ai reviews
- Trustpilot: sigma.ai reviews, all languages
- Trustpilot: sigma.ai 5-star reviews, all languages
- Trustpilot: sigma-ai.com reviews (profile named Sigma Technologies)
- Trustpilot: sigma-ai.com reviews, all languages
- sigma-ai.com (redirects to sigma.ai, checked November 5, 2026)
- FTC Consumer Alert: That job offer text is probably a scam (April 30, 2026)
What Sigma AI pays
Third-party reports · as of 2026-11-05Researched rate card, third-party reports, as of 2026-11-05
Sigma AI states no pay: none of the 88 postings on its careers board (careers.sigma.ai, its Teamtailor feed, read 5 Nov 2026) names a rate. The only dated worker figures found are on Glassdoor's hourly pay page for Sigma AI in Madrid (read 29 Oct 2026 in the company's browser; 9 of its 46 salary reports visible without sign-in, in euros, no dates on the rows): Transcriptor €7 to €9 an hour (11 reports), Transcriber €9 to €42 (4 reports), Transcriptionist €7 to €8 (2), Transcriptora €9 (2) and Language Transcriptor €9 to €10 (1). On 5 Nov 2026 its Madrid salaries page, read signed out in the company's browser, showed the same 46 job titles and the same number of reports for each of these titles, in monthly figures (most €1K to €2K a month), so the hourly ranges above stand as read on 29 Oct 2026. They are self-reported and mostly from Madrid, so the card gives no US dollar figure. The earlier card's ZipRecruiter figures (average about $39.54 an hour, most $23 to $51) and '€0.7 per audio minute' could not be re-read: ZipRecruiter's page redirected to its Irish site and showed no Sigma AI figures (29 Oct 2026), so they are left out.
| Role | Kind of work | Researched pay |
|---|---|---|
| Linguistic annotator / labeler | Data Annotation | Not stated in its postings |
| Transcriber | Transcription & Audio | €7–€9/hr most reported (Glassdoor, Madrid; up to €42) |
| Translator / linguist expert | Multilingual | Not stated in its postings |
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The work Sigma AI hires for
Each links to what the work involves, who hires for it, and what it pays across the market.
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How to get started on Sigma AI
Researched Nov 2026Find the project for your language on careers.sigma.ai, click Apply for this job, complete the mandatory tests Sigma emails you (check spam), provide any identity and credential documents it asks for, then sign a freelance commercial contract and work remotely on Sigma's online platform; Sigma publishes no pay rate or payment terms, so ask for them before you start.
Who can join
- Native or fluent command of the project's language, able to listen and write without spelling mistakes. Most remote projects also ask for fluent English and basic computer skills. Experience is preferred but not required: on 5 November 2026 the Cantonese post and 18 other posts on Sigma's careers feed name computational linguistics, corpus analysis, language data annotation or LLM training, and 61 posts name data annotation or content rating.
- For translator roles, more: the Romanian Translator post asks for a Bachelor's degree in Translation and Interpretation, native or near-native Romanian, fluent English and a solid command of linguistic theory and grammar.
- A computer with at least 4GB of RAM, a microphone and webcam, Windows 10 or macOS 13 Ventura or later with all updates, a stable internet connection, headphones and a secure, password-protected internet location. Audio-collection projects also need an Android phone; tablets and iOS devices are not supported.
- Documents that prove your identity and credentials. Every post says the candidate agrees to provide them on request, and that Sigma may withhold or terminate an offer if the evidence is not enough.
- Willingness to work as a freelancer: remote projects are offered under a commercial contract, not employment.
- For some projects, being in London or Madrid: on 5 November 2026, 15 of the 88 posts on Sigma's careers feed were on-site in London and 1 (Italian) in Madrid, and they ask for English (in Madrid, English or Spanish) good enough to work in an office.
Step by step
- 1
Find the post for your language
Sigma recruits per language and per variety, not through one general sign-up. On 5 November 2026 its careers feed held 88 posts: 72 remote, 15 on-site in London and 1 on-site in Madrid. The newest were a remote Czech and English post (4 November), on-site London posts for Serbian and Slovak (30 October) and Swedish (27 October), and a remote Cantonese post (19 October).
- 2
Check the requirements and your equipment
Read the language, skills and technical requirements in the post before you apply. Audio-collection work needs an Android phone or a Windows computer; tablets and iOS devices are not supported.
- 3
Apply on careers.sigma.ai
Click 'Apply for this job' and follow the instructions. Apply directly: Sigma says it does not hire through third parties, and no agents or intermediaries are authorized to take part in the relationship.
- 4
Complete the emailed tests
After you apply, Sigma emails you the required tests, which are mandatory to move forward; check your spam folder too. Sigma says it may use AI systems to evaluate the tests, for instance the transcribed content you submit.
- 5
Send identity and credential documents if asked
Sigma can ask for any documentation it reasonably needs to verify who you are and your credentials, and may withhold or end an offer without it.
- 6
Read and sign the freelance contract
Remote work is offered to freelancers under a commercial contract. One December 2025 Trustpilot reviewer says her contract came through Sigma's US office with one-sided clauses and urges legal advice before signing, so read it closely and ask about the rate and payment terms first.
- 7
Start work on Sigma's platform
All tasks are remote, on an online platform available 24/7. Some projects are short: the French voice-command audio project asks for 500 short utterances over two recording sessions, about 2.5 hours in all, with project manuals and optional kick-off sessions.
Language tests emailed after you apply
Every remote post says that after you apply you receive an email with the required tests, and that they are mandatory to move forward. Sigma says it may use AI systems to evaluate them, for instance the transcribed content you provide. Sigma does not publish what the tests contain, how long they take, the pass mark or whether they are paid; applicants on Trustpilot describe transcribing test audio clips and, for some roles, a translation test.
Format
Emailed tests in the project's language. Applicant reports describe audio transcription (one says five audio files, about 35 minutes in all) and, for translator roles, a translation test with its own guideline.
How to prepare
- Check your inbox and spam folder right after applying: the tests arrive by email.
- Transcribe exactly what you hear and spell everything correctly. Every post asks for people able to listen and write without spelling mistakes.
- Use headphones in a quiet place on a computer that meets the post's requirements (4GB of RAM, microphone, updated Windows 10 or macOS 13).
- Read the test guidelines in full before you start, and ask questions early: one applicant said a translation guideline was confusing and his email asking for clarification went unanswered.
- Have your ID and any degree certificate ready, since Sigma may ask for proof of identity and credentials.
Why people get rejected
- Spelling mistakes or an inaccurate transcription, the one skill every post insists on.
- Not completing the mandatory tests, or missing the email in a spam folder.
- Not giving enough evidence of identity or credentials: Sigma says it may then withhold or terminate an offer.
- Equipment that does not qualify, such as an iPhone or a tablet for an audio-collection project.
Sigma publishes no timeline from application to first paid work, and no step tells you when you have been turned down. Some applicants on Trustpilot say they finished the tests and never heard back. Projects also differ widely in size, so being accepted onto one may not mean ongoing work.
Sigma does not publish how or when freelancers are paid. Its posts offer remote work to freelancers under a commercial contract, and none of the 88 posts on its careers feed on 5 November 2026 stated a rate. Ask for the rate, its unit (per hour, per audio minute or per task), the payment method and the schedule in writing before you start.
Tips to get accepted
- Apply only through careers.sigma.ai. Sigma says it does not hire through third parties, so anyone offering Sigma work through an agency, a fee or a chat app is not Sigma.
- Apply to every post that matches your languages. Sigma recruits per language and variety, and combinations such as Korean and Chinese, Korean and Japanese, or German, Russian and English have their own posts.
- Ask for the rate before you put hours into tests or work. Reviewers describe transcription paid per minute of audio, unpaid meetings and tests, and one says his wife had not been paid for about 80 hours over two weeks.
- Read the freelance contract before signing and question anything one-sided; one reviewer recommends getting legal advice first.
- Keep an Android phone available if you want audio-collection projects: they do not support iOS devices or tablets.
- Use the project manuals and optional kick-off sessions that audio projects offer to clear up technical or procedural questions before you record.
What isn't public
- Sigma publishes no pay rates: none of its 88 posts on 5 November 2026 stated one. It also publishes no payment method, schedule, currency or minimum for freelancers.
- It does not say what its tests contain, how long they take, how they are scored or whether they are paid; Trustpilot reviewers describe them as unpaid.
- There is no published timeline and no stated way you are told you were not selected; some applicants say they never heard back after the tests.
- Which Sigma company signs your contract (Spain, the UK or the US) is not stated in the posts; one reviewer says hers came from the US office.
- Sigma's own figures disagree (read 5 November 2026): its FAQ and About page say it was founded in 2008 and covers 500+ languages (About: 25,000+ annotators), its homepage says 18+ years, 700+ languages and 70,000+ experts, its careers site more than 2,500 people, and its job posts claim over 30 years of experience and 200+ or 700+ languages.
- The 15 on-site London posts and the on-site Madrid post do not say whether they are freelance or employment, and do not describe the remote tests; the careers feed's job data on 5 November 2026 labels those 16 posts full-time and the 72 remote posts temporary.
- Public worker reviews are few: on 29 October 2026 Trustpilot had 7 reviews of sigma.ai and 8 of sigma-ai.com (a domain that redirects to sigma.ai, listed as Sigma Technologies, all 1-star), and Glassdoor refused a plain fetch, so it is not used here.
Sources (11)
- Sigma AI Careers: job feed (88 posts, read November 5, 2026)
- Sigma AI Careers: Cantonese Chinese (Traditional script) Linguistic Projects (Remote), posted October 19, 2026
- Sigma AI Careers: Romanian Translator (Remote)
- Sigma AI Careers: French Audio Collection Projects (Remote)
- Sigma AI Careers (Madrid, London and Miami, more than 2,500 people; read November 5, 2026)
- Sigma AI: FAQs (founded 2008 in Madrid, offices, 500+ languages; read November 5, 2026)
- Sigma AI: About
- Sigma AI: homepage
- Trustpilot: sigma.ai reviews, all languages
- Trustpilot: sigma-ai.com reviews (profile named Sigma Technologies)
- sigma-ai.com (redirects to sigma.ai, checked November 5, 2026)
From the forum
Ask the people doing Sigma AI work what only they can tell you.
Frequently asked questions
Is Sigma AI legit?
Mostly. Sigma AI is a real Madrid data company, founded in 2008 with offices in London and Miami, but it publishes no freelance rates or payment terms, and its few public worker reviews are mostly negative. Its job posts state no pay, applicants report unpaid tests that go unanswered, and workers describe per-minute transcription pay and one-sided contract terms, so ask for the rate and read the contract before you invest time.
Is Sigma AI a scam?
No. Sigma AI is a real company. No Sigma-specific impersonation cases turned up in a web search on 5 November 2026. Real openings are listed at careers.sigma.ai, and Sigma's job posts say it never hires through agents or other third parties. Other companies share the Sigma name, so check the domain is sigma.ai. Never pay to get work; fake recruiters often start on text, WhatsApp or Telegram.
Does Sigma AI pay?
Yes. Genuine flexibility, but worker sentiment on pay is mixed-to-negative. Payouts: Freelance commercial contract; its postings and careers site publish no payment method or schedule (read 5 Nov 2026). Sigma does not publish how or when freelancers are paid. Its posts offer remote work to freelancers under a commercial contract, and none of the 88 posts on its careers feed on 5 November 2026 stated a rate. Ask for the rate, its unit (per hour, per audio minute or per task), the payment method and the schedule in writing before you start.
How much does Sigma AI pay?
Not stated; Madrid transcribers report ~€7–€9/hr (Glassdoor). Sigma AI states no pay: none of the 88 postings on its careers board (careers.sigma.ai, its Teamtailor feed, read 5 Nov 2026) names a rate. The only dated worker figures found are on Glassdoor's hourly pay page for Sigma AI in Madrid (read 29 Oct 2026 in the company's browser; 9 of its 46 salary reports visible without sign-in, in euros, no dates on the rows): Transcriptor €7 to €9 an hour (11 reports), Transcriber €9 to €42 (4 reports), Transcriptionist €7 to €8 (2), Transcriptora €9 (2) and Language Transcriptor €9 to €10 (1). On 5 Nov 2026 its Madrid salaries page, read signed out in the company's browser, showed the same 46 job titles and the same number of reports for each of these titles, in monthly figures (most €1K to €2K a month), so the hourly ranges above stand as read on 29 Oct 2026. They are self-reported and mostly from Madrid, so the card gives no US dollar figure. The earlier card's ZipRecruiter figures (average about $39.54 an hour, most $23 to $51) and '€0.7 per audio minute' could not be re-read: ZipRecruiter's page redirected to its Irish site and showed no Sigma AI figures (29 Oct 2026), so they are left out.
Is Sigma AI worth it?
Sigma AI pays Not stated; Madrid transcribers report ~€7–€9/hr (Glassdoor) (third-party reports). It suits flexible microtask income rather than a dependable hourly wage. Worker sentiment: Trustpilot 2.6/5 (7 reviews) · Trustpilot (sigma-ai.com) 2.2/5 (8 reviews).
How does Sigma AI pay out?
Freelance commercial contract; its postings and careers site publish no payment method or schedule (read 5 Nov 2026).
Where can you work for Sigma AI?
Language-driven: each posting asks for fluent or native speakers of a named language, a few for a pair or trio (Czech and English, Korean and Japanese; German, Russian and English). Of its 88 postings on 5 Nov 2026, 72 are tagged Fully Remote, 15 are on-site in London and 1 in Madrid (careers.sigma.ai/jobs.json). Its postings describe offices in Spain, the US and the UK.
How do I get accepted on Sigma AI?
Apply to the post for your language on careers.sigma.ai, complete the mandatory tests Sigma emails you, and provide any identity and credential documents it asks for. Remote work is then offered to freelancers under a commercial contract.
Does Sigma AI have a test?
Yes. After you apply, Sigma emails you the required tests, which are mandatory, and says it may use AI to evaluate them, for instance your transcribed content. It does not publish their length, pass mark or whether they are paid.
How does Sigma AI pay its freelancers?
Sigma publishes no payment method or schedule. Trustpilot reviewers describe transcription paid per minute of audio; one says payments are regular, while others describe unpaid tests, unpaid meetings and unpaid hours.
Can I work for Sigma AI from home?
Yes, for most projects. On 5 November 2026, 72 of the 88 posts on its careers feed were remote, 15 were on-site in London and 1 was on-site in Madrid.
What equipment do I need for Sigma AI?
A computer with at least 4GB of RAM, a microphone and webcam, Windows 10 or macOS 13 Ventura or later, headphones and stable internet. Audio-collection projects also need an Android phone; tablets and iOS devices are not supported.
Do I need a degree to work for Sigma AI?
Not for most linguistic projects, which ask for fluency, correct spelling and basic computer skills. Translator roles are stricter: the Romanian Translator post asks for a Bachelor's degree in Translation and Interpretation.
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Short of experts at Sigma AI? We find the experts (you contract them yourself) or we run the project (we deliver the expert work).