lm-sys/FastChat

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An open platform for training, serving, and evaluating large language models. Release repo for Vicuna and Chatbot Arena.

Stars: 39.5k
Forks: 4.8k
Open beginner issues: 2
Indexed issues: 899

Dominant language: Python
License: Apache-2.0
Last GitHub push: Jun 2, 2025
Latest indexed: Sep 19, 2026
Contributing guide: No contributing guide
Code of conduct: No code of conduct
Beginner labels: good first issue help wanted
PR merge metrics: No merged PRs in 30d

Beginner friendly Everything

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899 issues indexed so far

[Bug] Arena Embedded Space Login Failure (401 "User not found") Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

lm-sys/FastChat#3933 · Opened Sep 5, 2026
[Bug Report] Multiple regressions: Font rendering asset failure, broken keyword search, and generation timeouts Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

lm-sys/FastChat#3930 · Opened Sep 2, 2026
[HTTPXodus] Consider migrating from `httpx` to `httpx2` (the actively maintained fork) Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

lm-sys/FastChat#3929 · Opened Sep 2, 2026
OpenAI-compat: gen_api_answer.py --openai-api-base /v1, not the API server Open

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

lm-sys/FastChat#3928 · Opened Aug 28, 2026
Would an EvalPort-format export of MT-Bench be welcome? Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

lm-sys/FastChat#3926 · Opened Aug 22, 2026
i am in batte mode and option b is not working i am clicking retry again and again there is much bug in it feel jammed Open

Difficulty 3/5 1-2 days Newbie friendliness 20/100

lm-sys/FastChat#3925 · Opened Aug 18, 2026
A/B Testing mode stuck indefinitely on "Generating..." status Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3924 · Opened Aug 17, 2026
[Model Request] Apollo-VL-Edge-3B (Sub-5B VLM) Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3923 · Opened Aug 14, 2026
[Model Submission] OpenAI-Compatible API — Xiaothink-T17-RWKV5-MLA-0.6B-Frontend Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

lm-sys/FastChat#3922 · Opened Aug 10, 2026
[Model Submission] Sylor Pro / Sylor Flash — OpenAI-Compatible API Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3917 · Opened Jul 26, 2026
UI build timer shows extremely high duration (2940+ minutes) and gets stuck after failed edit attempts Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3915 · Opened Jul 26, 2026
Battle MOOd option B Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3914 · Opened Jul 22, 2026
Battle Mode Option B crashes while generating my Ghousia Electronics Desktop Software project (Trace ID: e6bf2e90ea76d4411a36de2d7d22391a) Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

lm-sys/FastChat#3912 · Opened Jul 22, 2026
[BUG] [Agent Mode] Chat interface response index mismatch / shift after cross-tab logout-login Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

lm-sys/FastChat#3910 · 1 comment · Opened Jul 19, 2026
UI Formatting issue in question asked Open

Difficulty 3/5 1-2 days Newbie friendliness 42/100

lm-sys/FastChat#3904 · 1 comment · Opened Jul 16, 2026
Sharing: Alternative API access for developers without international credit cards Open

Difficulty 5/5 Over a week Newbie friendliness 10/100

lm-sys/FastChat#3902 · Opened Jul 12, 2026
[Model Request] Add support for Cartik/Sonexa-1-Chat Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

lm-sys/FastChat#3901 · Opened Jul 10, 2026
Add TemuClaude to Chatbot Arena — OpenAI-compatible API endpoint Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

lm-sys/FastChat#3899 · Opened Jul 7, 2026
Arena.ai rejects python files during upload Open

Difficulty 3/5 1-2 days Newbie friendliness 62/100

lm-sys/FastChat#3888 · Opened Jun 20, 2026
Unauthenticated SSRF and worker/model spoofing via the controller /register_worker endpoint Open

Difficulty 4/5 3-5 days Newbie friendliness 38/100

lm-sys/FastChat#3886 · Opened Jun 12, 2026
UI/UX improvement: Add confirmation for "Clear History" button Open

Difficulty 2/5 1-3 hours Newbie friendliness 64/100

lm-sys/FastChat#3881 · Opened May 30, 2026
🎉 Your project is featured in awesome-ai-chat-apps Open

Difficulty 5/5 Over a week Newbie friendliness 15/100

lm-sys/FastChat#3877 · 1 comment · Opened May 24, 2026
[Bug] Stuck Generation Loop in Main Account (WebSocket Deadlock) Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3876 · 1 comment · Opened May 24, 2026
Account Issue - Arena Not Responding when Logged In Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3875 · 7 comments · 1 reaction · Opened May 23, 2026
Vulnerability Report: SSRF + Arbitrary Local File Read in fastchat.utils.load_image via unvalidated image URL/path Open

Difficulty 5/5 Over a week Newbie friendliness 42/100

lm-sys/FastChat#3873 · 1 comment · Opened May 17, 2026
Cloudflare Block Issue When Accessing arena.ai - Ray ID: 9fb7f9129c4d5e16 Open

Difficulty 5/5 Over a week Newbie friendliness 15/100

lm-sys/FastChat#3871 · Opened May 14, 2026
Direct Chat stuck on infinite generation Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3870 · Opened May 11, 2026
Infinite Loading Loop on Long Conversation (2+ Months of Lore / High Context) Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3866 · 1 comment · Opened May 6, 2026
Session Hang on Long Conversations - No Error Feedback Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

lm-sys/FastChat#3861 · 2 comments · Opened Apr 22, 2026
Suspicious model "rotten-apple" appeared in public arena Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

lm-sys/FastChat#3847 · Opened Apr 11, 2026
[Security] Content Moderation Bypass in Arena Side-by-Side Views (Incomplete Fix for 34eca62) Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

lm-sys/FastChat#3834 · 2 comments · Opened Apr 5, 2026
[Security] Denial of Service via Blocking Event Loop in Model Workers (Incomplete Fix for ff66426) Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

lm-sys/FastChat#3833 · Opened Apr 5, 2026
Claude opus models not available Open

Difficulty 3/5 1-2 days Newbie friendliness 38/100

lm-sys/FastChat#3832 · 2 comments · Opened Apr 4, 2026
Request Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

lm-sys/FastChat#3824 · Opened Mar 30, 2026
Account Appeal - kaixinwu726@gmail Open

Difficulty 5/5 Over a week Newbie friendliness 1/100

lm-sys/FastChat#3823 · 1 comment · Opened Mar 27, 2026
📋 Documentation Enhancement Suggestion Open

Difficulty 2/5 1-3 hours Newbie friendliness 30/100

lm-sys/FastChat#3819 · Opened Mar 19, 2026
Regarding issue with output format for Vicuna (lmsys/vicuna-7b-v1.5) using fastchat/serve/huggingface_api.py Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

lm-sys/FastChat#3795 · 1 comment · Opened Mar 11, 2026
Moderation Filter Bypass via Wrong State Index in Arena Side-by-Side Views Open

Difficulty 2/5 1-3 hours Newbie friendliness 55/100

lm-sys/FastChat#3794 · Opened Mar 11, 2026
[Security] Denial of Service via Blocking Event Loop in Model Workers (Incomplete Fix for ff66426) Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

lm-sys/FastChat#3793 · Opened Mar 11, 2026
🌍 Join Agent World - 一个为所有AI建造的世界 Open

Difficulty 5/5 Over a week Newbie friendliness 1/100

lm-sys/FastChat#3789 · Opened Mar 10, 2026
"Something went wrong with this response, please try again" error mssage Open

Difficulty 5/5 Over a week Newbie friendliness 18/100

lm-sys/FastChat#3782 · 2 comments · Opened Mar 8, 2026
Eliminating CAPTCHAs via a "Vote-to-Access" Economy & In-Site Session Locking Open

Difficulty 5/5 Over a week Newbie friendliness 20/100

lm-sys/FastChat#3780 · 2 comments · 2 reactions · Opened Feb 28, 2026
Cloudflare Block Issue When Accessing arena.ai Open

Difficulty 4/5 3-5 days Newbie friendliness 15/100

lm-sys/FastChat#3779 · 4 comments · 3 reactions · Opened Feb 26, 2026
Pickle Deserialization RCE via torch.load() Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

lm-sys/FastChat#3777 · Opened Feb 25, 2026
SSRF via Unauthenticated Worker Registration Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

lm-sys/FastChat#3776 · Opened Feb 25, 2026
email authentication callback URL issue Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

lm-sys/FastChat#3774 · Opened Feb 11, 2026
compute_bootstrap_elo illegal arguments? Open

Difficulty 2/5 1-3 hours Newbie friendliness 45/100

lm-sys/FastChat#3769 · 1 comment · Opened Jan 31, 2026
Excessive False Positives in Image Generation (Works in ChatGPT, fails in Lmarena) Open

Difficulty 4/5 3-5 days Newbie friendliness 30/100

lm-sys/FastChat#3768 · Opened Jan 7, 2026
Cloudflare IP block on lmarena.ai Open

Difficulty 5/5 Over a week Newbie friendliness 10/100

lm-sys/FastChat#3767 · Opened Jan 4, 2026
Not telling the models what the correct date is Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

lm-sys/FastChat#3766 · Opened Jan 2, 2026

lm-sys/FastChat

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